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Sample records for suspension volumes apply

  1. 30 CFR 203.73 - How do suspension volumes apply to natural gas?

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 2 2010-07-01 2010-07-01 false How do suspension volumes apply to natural gas... suspension volumes apply to natural gas? You must measure natural gas production under the royalty-suspension volume as follows: 5.62 thousand cubic feet of natural gas, measured in accordance with 30 CFR part 250...

  2. Applying analytical ultracentrifugation to nanocrystal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Jamison, Jennifer A; Krueger, Karl M; Mayo, J T; Yavuz, Cafer T; Redden, Jacina J; Colvin, Vicki L, E-mail: colvin@rice.ed [Department of Chemistry, Rice University, 6100 Main Street, MS-60, Houston, TX 77005 (United States)

    2009-09-02

    While applied frequently in physical biochemistry to the study of protein complexes, the quantitative use of analytical ultracentrifugation (AUC) for nanocrystal analysis is relatively rare. Its application in nanoscience is potentially very powerful as it provides a measure of nanocrystal density, size and structure directly in the solution phase. Towards that end, this paper examines the best practices for applying data collection and analysis methods for AUC, geared towards the study of biomolecules, to the unique problems of nanoparticle analysis. Using uniform nanocrystals of cadmium selenide, we compared several schemes for analyzing raw sedimentation data. Comparable values of the mean sedimentation coefficients (s-value) were found using several popular analytical approaches; however, the distribution in sample s-values is best captured using the van Holde-Weischt algorithm. Measured s-values could be reproducibly collected if sample temperature and concentration were controlled; under these circumstances, the variability for average sedimentation values was typically 5%. The full shape of the distribution in s-values, however, is not easily subjected to quantitative interpretation. Moreover, the selection of the appropriate sedimentation speed is crucial for AUC of nanocrystals as the density of inorganic nanocrystals is much larger than that of solvents. Quantitative analysis of sedimentation properties will allow for better agreement between experimental and theoretical models of nanocrystal solution behavior, as well as providing deeper insight into the hydrodynamic size and solution properties of nanomaterials.

  3. Regulation of Cytoplasmic and Vacuolar Volumes by Plant Cells in Suspension Culture

    DEFF Research Database (Denmark)

    Owens, Trevor; Poole, Ronald J

    1979-01-01

    Quantitative microscopical measurements have been made of the proportion of cell volume occupied by cytoplasm in a cell suspension culture derived from cotyledons of bush bean (cv. Contender). On a 7-day culture cycle, the content of cytoplasm varies from 25% at the time of transfer to 45% at the...

  4. Brownian Dynamics of a Suspension of Particles with Constrained Voronoi Cell Volumes

    KAUST Repository

    Singh, John P.; Walsh, Stuart D. C.; Koch, Donald L.

    2015-01-01

    © 2015 American Chemical Society. Solvent-free polymer-grafted nanoparticle fluids consist of inorganic core particles fluidized by polymers tethered to their surfaces. The attachment of the suspending fluid to the particle surface creates a strong penalty for local variations in the fluid volume surrounding the particles. As a model of such a suspension we perform Brownian dynamics of an equilibrium system consisting of hard spheres which experience a many-particle potential proportional to the variance of the Voronoi volumes surrounding each particle (E = α(Vi-V0)2). The coefficient of proportionality α can be varied such that pure hard sphere dynamics is recovered as α → 0, while an incompressible array of hairy particles is obtained as α →. As α is increased the distribution of Voronoi volumes becomes narrower, the mean coordination number of the particle increases and the variance in the number of nearest neighbors decreases. The nearest neighbor peaks in the pair distribution function are suppressed and shifted to larger radial separations as the constraint acts to maintain relatively uniform interstitial regions. The structure factor of the model suspension satisfies S(k=0) → 0 as α → in accordance with expectation for a single component (particle plus tethered fluid) incompressible system. The tracer diffusivity of the particles is reduced by the volume constraint and goes to zero at φ 0.52, indicating an earlier glass transition than has been observed in hard sphere suspensions. The total pressure of the suspension grows in proportion to (αkBT)1/2 as the strength of the volume-constraint potential grows. This stress arises primarily from the interparticle potential forces, while the hard-sphere collisional contribution to the stress is suppressed by the volume constraint.

  5. Brownian Dynamics of a Suspension of Particles with Constrained Voronoi Cell Volumes

    KAUST Repository

    Singh, John P.

    2015-06-23

    © 2015 American Chemical Society. Solvent-free polymer-grafted nanoparticle fluids consist of inorganic core particles fluidized by polymers tethered to their surfaces. The attachment of the suspending fluid to the particle surface creates a strong penalty for local variations in the fluid volume surrounding the particles. As a model of such a suspension we perform Brownian dynamics of an equilibrium system consisting of hard spheres which experience a many-particle potential proportional to the variance of the Voronoi volumes surrounding each particle (E = α(Vi-V0)2). The coefficient of proportionality α can be varied such that pure hard sphere dynamics is recovered as α → 0, while an incompressible array of hairy particles is obtained as α →. As α is increased the distribution of Voronoi volumes becomes narrower, the mean coordination number of the particle increases and the variance in the number of nearest neighbors decreases. The nearest neighbor peaks in the pair distribution function are suppressed and shifted to larger radial separations as the constraint acts to maintain relatively uniform interstitial regions. The structure factor of the model suspension satisfies S(k=0) → 0 as α → in accordance with expectation for a single component (particle plus tethered fluid) incompressible system. The tracer diffusivity of the particles is reduced by the volume constraint and goes to zero at φ 0.52, indicating an earlier glass transition than has been observed in hard sphere suspensions. The total pressure of the suspension grows in proportion to (αkBT)1/2 as the strength of the volume-constraint potential grows. This stress arises primarily from the interparticle potential forces, while the hard-sphere collisional contribution to the stress is suppressed by the volume constraint.

  6. Reliability of tanoak volume equations when applied to different areas

    Science.gov (United States)

    Norman H. Pillsbury; Philip M. McDonald; Victor Simon

    1995-01-01

    Tree volume equations for tanoak (Lithocarpus densiflorus) were developed for seven stands throughout its natural range and compared by a volume prediction and a parameter difference method. The objective was to test if volume estimates from a species growing in a local, relatively uniform habitat could be applied more widely. Results indicated...

  7. Fault Detection Based on Tracking Differentiator Applied on the Suspension System of Maglev Train

    Directory of Open Access Journals (Sweden)

    Hehong Zhang

    2015-01-01

    Full Text Available A fault detection method based on the optimized tracking differentiator is introduced. It is applied on the acceleration sensor of the suspension system of maglev train. It detects the fault of the acceleration sensor by comparing the acceleration integral signal with the speed signal obtained by the optimized tracking differentiator. This paper optimizes the control variable when the states locate within or beyond the two-step reachable region to improve the performance of the approximate linear discrete tracking differentiator. Fault-tolerant control has been conducted by feedback based on the speed signal acquired from the optimized tracking differentiator when the acceleration sensor fails. The simulation and experiment results show the practical usefulness of the presented method.

  8. Fuzzy-Skyhook Control for Active Suspension Systems Applied to a Full Vehicle Model

    Directory of Open Access Journals (Sweden)

    Aref M.A. Soliman

    2012-04-01

    Full Text Available Nowadays, most modern vehicles are equipped with controlled suspension systems for improving the vehicle ride comfort. Therefore, this paper is concerned with a theoretical study for the ride comfort performance of the vehicle. The theoretical investigation includes a suggestion of an active suspension system controller using fuzzy-skyhook control theory, which offers new opportunities for the improvement of vehicle ride performance. The ride comfort of the active suspension system has been evaluated using a 7 degree of freedom full vehicle mathematical model. The simulation results are presented in the time and frequency domain, also in terms of RMS values, and it’s shown that the proposed active suspension system with fuzzy-skyhook control improved the vehicle ride quality in terms of body acceleration, suspension working space and dynamic tyre load in comparison with the passive and skyhook suspension systems.

  9. Conception and development of an optical methodology applied to long-distance measurement of suspension bridges dynamic displacement

    International Nuclear Information System (INIS)

    Martins, L Lages; Ribeiro, A Silva; Rebordão, J M

    2013-01-01

    This paper describes the conception and development of an optical system applied to suspension bridge structural monitoring, aiming real-time and long-distance measurement of dynamical three-dimensional displacement, namely, in the central section of the main span. The main innovative issues related to this optical approach are described and a comparison with other optical and non-optical measurement systems is performed. Moreover, a computational simulator tool developed for the optical system design and validation of the implemented image processing and calculation algorithms is also presented

  10. 30 CFR 203.71 - How does MMS allocate a field's suspension volume between my lease and other leases on my field?

    Science.gov (United States)

    2010-07-01

    ... RATES OCS Oil, Gas, and Sulfur General Royalty Relief for Pre-Act Deep Water Leases and for Development... or post-November 2000 deep water lease to your field after we approve your application We will not..., or the minimum suspension volume of the authorized field, whichever is greater (i) You toll the time...

  11. The spectral volume method as applied to transport problems

    International Nuclear Information System (INIS)

    McClarren, Ryan G.

    2011-01-01

    We present a new spatial discretization for transport problems: the spectral volume method. This method, rst developed by Wang for computational fluid dynamics, divides each computational cell into several sub-cells and enforces particle balance on each of these sub-cells. Also, these sub-cells are used to build a polynomial reconstruction in the cell. The idea of dividing cells into many cells is a generalization of the simple corner balance and other similar schemes. The spectral volume method preserves particle conservation and preserves the asymptotic diffusion limit. We present results from the method on two transport problems in slab geometry using discrete ordinates and second through sixth order spectral volume schemes. The numerical results demonstrate the accuracy and preservation of the diffusion limit of the spectral volume method. Future work will explore possible bene ts of the scheme for high-performance computing and for resolving diffusive boundary layers. (author)

  12. Study of the aeraulic re-suspension applied to the dust issue in the future ITER tokamak

    International Nuclear Information System (INIS)

    Rondeau, Anthony

    2015-01-01

    In ITER, a loss of vacuum accident is likely to re-suspend particles produced and deposited on the torus walls. The thesis purpose is to provide reliable experimental data to develop and validate a re-suspension model, taking into account the low pressure and predicting the amount of particles mobilized during such event. Experiments were carried out as a function of key parameters - particle diameter, friction velocity and density of the atmosphere - entering in the re-suspension mechanism. The size distribution of tungsten particles produced in tokamaks shows diameters from 0.1 to 10 μm. The experimental data of tungsten particle monolayer deposits re-suspension are in good agreement with the Rock'n Roll model when the particles are only mobilised by the fluid. However, a mobilisation of fine particles by clustering, no taken into account in re-suspension models, was highlighted. My experiments have also revealed the importance of the multilayers deposit structure (porosity and thickness) in the re-suspension mechanism with, here again, a mobilisation by particle clustering. The effect of low pressure in the re-suspension mechanism was studied between 10 and 1,000 mbar and shows a friction reduction in the airflow forces at low pressure. Finally, measurements of the MES phenomenon kinetics highlighted three distinct regions with a short-term effect, a long-term effect and a transition region which must be taken into account in a MES calculation. (author)

  13. Unveiling the relationships among the viscosity equations of glass liquids and colloidal suspensions for obtaining universal equations with the generic free volume concept.

    Science.gov (United States)

    Hao, Tian

    2015-09-14

    The underlying relationships among viscosity equations of glass liquids and colloidal suspensions are explored with the aid of free volume concept. Viscosity equations of glass liquids available in literature are focused and found to have a same physical basis but different mathematical expressions for the free volume. The glass transitions induced by temperatures in glass liquids and the percolation transition induced by particle volume fractions in colloidal suspensions essentially are a second order phase transition: both those two transitions could induce the free volume changes, which in turn determines how the viscosities are going to change with temperatures and/or particle volume fractions. Unified correlations of the free volume to both temperatures and particle volume fractions are thus proposed. The resulted viscosity equations are reducible to many popular viscosity equations currently widely used in literature; those equations should be able to cover many different types of materials over a wide temperature range. For demonstration purpose, one of the simplified versions of those newly developed equations is compared with popular viscosity equations and the experimental data: it can well fit the experimental data over a wide temperature range. The current work reveals common physical grounds among various viscosity equations, deepening our understanding on viscosity and unifying the free volume theory across many different systems.

  14. Annual Review of Applied Linguistics, Volume 5, 1984.

    Science.gov (United States)

    Kaplan, Robert B., Ed.

    This volume of the annual review includes introductory remarks by G. Richard Tucker and these papers: "Current Issues in Bilingualism: An Update of Directions in Research" (Braj B. Kachru); "Psycholinguistics: Application. The Writing System as a Native Language for the Deaf" (Danny D. Steinberg); "Sociolinguistics: Theory" (Monica Heller);…

  15. IMAGE information monitoring and applied graphics software environment. Volume 4. Applications description

    International Nuclear Information System (INIS)

    Hallam, J.W.; Ng, K.B.; Upham, G.L.

    1986-09-01

    The EPRI Information Monitoring and Applied Graphics Environment (IMAGE) system is designed for 'fast proto-typing' of advanced concepts for computer-aided plant operations tools. It is a flexible software system which can be used for rapidly creating, dynamically driving and evaluating advanced operator aid displays. The software is written to be both host computer and graphic device independent. This four volume report includes an Executive Overview of the IMAGE package (Volume 1), followed by Software Description (Volume II), User's Guide (Volume III), and Description of Example Applications (Volume IV)

  16. Vector velocity volume flow estimation: Sources of error and corrections applied for arteriovenous fistulas

    DEFF Research Database (Denmark)

    Jensen, Jonas; Olesen, Jacob Bjerring; Stuart, Matthias Bo

    2016-01-01

    radius. The error sources were also studied in vivo under realistic clinical conditions, and the theoretical results were applied for correcting the volume flow errors. Twenty dialysis patients with arteriovenous fistulas were scanned to obtain vector flow maps of fistulas. When fitting an ellipsis......A method for vector velocity volume flow estimation is presented, along with an investigation of its sources of error and correction of actual volume flow measurements. Volume flow errors are quantified theoretically by numerical modeling, through flow phantom measurements, and studied in vivo...

  17. Analysis of vibroprotection characteristics of pneumatic relaxation seat suspension with capability of vibration energy recuperation

    Directory of Open Access Journals (Sweden)

    Lyashenko Mikhail

    2017-01-01

    Full Text Available This paper proposes mechanism and control algorithm for pneumatic relaxation system of suspension with vibration energy recuperation applied to standard vehicle operator seat (“Sibeko” company. Mathematical model of the seat pneumatic relaxation suspension with two additional air volumes was created. Pneumatic motor – recuperator activated by means of air flow from the one additional volume to another is installed in air piping between additional volumes. Computational research was made in Matlab/Simulink. Amplitude-frequency characteristics of transmission coefficient for standard and proposed suspensions were plotted for preliminary evaluation of vibration protection properties of seat suspension. Performed comparative analysis of amplitude-frequency characteristics shows that noticeable improvement of vibration protection properties of pneumatic relaxation suspension system with vibration energy recuperation in comparison with standard system both in region of resonance disturbances and in above-resonance region. Main ways for further improvement of vibration protection properties of proposed system were marked out.

  18. Origins of microstructural transformations in charged vesicle suspensions: the crowding hypothesis.

    Science.gov (United States)

    Seth, Mansi; Ramachandran, Arun; Murch, Bruce P; Leal, L Gary

    2014-09-02

    It is observed that charged unilamellar vesicles in a suspension can spontaneously deflate and subsequently transition to form bilamellar vesicles, even in the absence of externally applied triggers such as salt or temperature gradients. We provide strong evidence that the driving force for this deflation-induced transition is the repulsive electrostatic pressure between charged vesicles in concentrated suspensions, above a critical effective volume fraction. We use volume fraction measurements and cryogenic transmission electron microscopy imaging to quantitatively follow both the macroscopic and microstructural time-evolution of cationic diC18:1 DEEDMAC vesicle suspensions at different surfactant and salt concentrations. A simple model is developed to estimate the extent of deflation of unilamellar vesicles caused by electrostatic interactions with neighboring vesicles. It is determined that when the effective volume fraction of the suspension exceeds a critical value, charged vesicles in a suspension can experience "crowding" due to overlap of their electrical double layers, which can result in deflation and subsequent microstructural transformations to reduce the effective volume fraction of the suspension. Ordinarily in polydisperse colloidal suspensions, particles interacting via a repulsive potential transform into a glassy state above a critical volume fraction. The behavior of charged vesicle suspensions reported in this paper thus represents a new mechanism for the relaxation of repulsive interactions in crowded situations.

  19. 39 CFR 320.9 - Revocation or amendment of suspensions.

    Science.gov (United States)

    2010-07-01

    ... SUSPENSION OF THE PRIVATE EXPRESS STATUTES § 320.9 Revocation or amendment of suspensions. These suspensions... of operations (in dollar or volume terms, whichever is larger) lower than that antedating the...

  20. Novas técnicas de reometria aplicadas a suspensões cerâmicas Novel rheometric techniques applied to ceramic suspensions

    Directory of Open Access Journals (Sweden)

    R. D. dos Anjos

    2005-06-01

    Full Text Available Suspensões cerâmicas com adequado comportamento reológico são imprescindíveis para a aplicação, adequação do processamento e otimização das propriedades finais dos produtos. No entanto, o uso de técnicas de reometria para análise de suspensões cerâmicas foi pouco explorado na literatura, quando comparado a outros sistemas, tais como polímeros fundidos. Desse modo, pretende-se demonstrar que o emprego de técnicas mais modernas de reometria permite uma nova compreensão desses materiais e das interações entre seus componentes. Neste trabalho foi estabelecida uma metodologia de análise para sistemas cerâmicos tendo como objeto de pesquisa uma suspensão de alumina e sol de sílica. Foi realizada uma série de medidas de viscosidade (eta, módulos de armazenamento (G' e de perda (G" e de força normal (Fn, cujos resultados servirão de base para estudos posteriores no mesmo sistema, visando aplicação em concretos refratários.Ceramic suspensions with suitable rheological properties are essential on application, process control and optimization of end products and properties. Nevertheless, the use of rheometric techniques to analyze such suspensions has been scarcely studied when compared to other systems, such as molten polymers. Therefore, in the present work, novel rheometric techniques will be presented which can allow a further understanding regarding these materials and the interaction among their components. A systematic study applying these techniques was established and the viscosity, storage modulus, loss modulus and normal force measurements were evaluated in a ceramic suspension containing alumina and silica sol. These results will be the fundaments for further studies, aiming their application on refractory castables.

  1. Mass-action model analysis of the apparent molar volume and heat capacity of pluronics in water and liposome suspensions at 25 °C.

    Science.gov (United States)

    Quirion, François; Meilleur, Luc; Lévesque, Isabelle

    2013-07-09

    Pluronics are block copolymers composed of a central block of polypropylene oxide and two side chains of polyethylene oxide. They are used in water to generate aggregates and gels or added to phospholipid suspensions to prepare microparticles for drug delivery applications. The structure of these systems has been widely investigated. However, little is known about the mechanisms leading to these structures. This investigation compares the apparent molar volumes and heat capacities of Pluronics F38, F108, F127, P85, P104, and P103 at 25 °C in water and in the presence of lecithin liposomes. The changes in molar volumes, heat capacities, and enthalpies generated by a mass-action model are in good agreement with the loss of hydrophobic hydration of the polypropylene oxide central block of the Pluronics. However, the molecularity of the endothermic transitions is much smaller than the aggregation numbers reported in the literature for the same systems. It is suggested that Pluronics go through dehydration of their central block to form unimolecular or small entities having a hydrophobic polypropylene oxide core. In water, these entities would assemble athermally to form larger aggregates. In the presence of liposomes, they would be transferred into the hydrophobic lecithin bilayers of the liposomes. Light transmission experiments suggest that the liposome suspensions are significantly altered only when the added Pluronics are in the dehydrated state.

  2. Sensitivity and uncertainty analyses applied to criticality safety validation. Volume 2

    International Nuclear Information System (INIS)

    Broadhead, B.L.; Hopper, C.M.; Parks, C.V.

    1999-01-01

    This report presents the application of sensitivity and uncertainty (S/U) analysis methodologies developed in Volume 1 to the code/data validation tasks of a criticality safety computational study. Sensitivity and uncertainty analysis methods were first developed for application to fast reactor studies in the 1970s. This work has revitalized and updated the existing S/U computational capabilities such that they can be used as prototypic modules of the SCALE code system, which contains criticality analysis tools currently in use by criticality safety practitioners. After complete development, simplified tools are expected to be released for general use. The methods for application of S/U and generalized linear-least-square methodology (GLLSM) tools to the criticality safety validation procedures were described in Volume 1 of this report. Volume 2 of this report presents the application of these procedures to the validation of criticality safety analyses supporting uranium operations where enrichments are greater than 5 wt %. Specifically, the traditional k eff trending analyses are compared with newly developed k eff trending procedures, utilizing the D and c k coefficients described in Volume 1. These newly developed procedures are applied to a family of postulated systems involving U(11)O 2 fuel, with H/X values ranging from 0--1,000. These analyses produced a series of guidance and recommendations for the general usage of these various techniques. Recommendations for future work are also detailed

  3. First experimental results of particle re-suspension in a low pressure wind tunnel applied to the issue of dust in fusion reactors

    Energy Technology Data Exchange (ETDEWEB)

    Rondeau, Anthony, E-mail: anthony.rondeau@irsn.fr [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES/SCA, Gif-sur-Yvette 91192 (France); Merrison, Jonathan; Iversen, Jens Jacob [Department of Physics and Astronomy, Institute for Storage Ring Facilities, 8000 Aarhus C (Denmark); Peillon, Samuel; Sabroux, Jean-Christophe; Lemaitre, Pascal; Gensdarmes, François [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), PSN-RES/SCA, Gif-sur-Yvette 91192 (France); Chassefière, Eric [Laboratoire Géosciences Paris Sud (GEOPS), UMR 8148, Université Paris Sud, 91403 Orsay Cedex (France)

    2015-10-15

    Highlights: • The first experimental data of dust re-suspension performed by controlled airflow (in terms of airflow velocity and fluid density). • The effect of the surrounding pressure in the re-suspension mechanism. • The friction (shear velocity) reduction at low pressure in the transient regime (Knudsen number close to one). • The importance of the adhesion forces between particles in dust mobilization by clustering. • The fact that the existing re-suspension models of the relevant literature do not take into account this clustering phenomenon. - Abstract: During the normal operating condition of the future ITER tokamak, a massive production of dust in the toroidal vacuum vessel is expected. This dust, originating from the erosion of tungsten and beryllium internal walls of the torus by the plasma, would be mobilized to some extent during a loss of vacuum accident (LOVA). For safety reasons, it is essential to quantify the re-suspended dust fraction during such an event. Here, we provide preliminary experimental data of dust re-suspension obtained in the wind tunnel of the European Space Agency (ESA) at low pressures (300, 130 and 10 mbar). The experimentations were performed with multilayer deposits. We used two powders with a median diameter at 15.5 μm and 21.8 μm. A negative influence of the low pressure in the re-suspension mechanism is observed. For example, given a re-suspension fraction of 10%, increasing friction shear velocities are derived for decreasing absolute pressures: 300 mbar/0.66 m s{sup −1}; 130 mbar/1.08 m s{sup −1}; and 10 mbar/1.84 m s{sup −1}. In addition, we highlight the friction reduction for Kundsen numbers greater than 0.1 by an analysis of the airflow forces.

  4. Administrative license suspension: Does length of suspension matter?

    Science.gov (United States)

    Fell, James C; Scherer, Michael

    2017-08-18

    Administrative license revocation (ALR) laws, which provide that the license of a driver with a blood alcohol concentration at or over the illegal limit is subject to an immediate suspension by the state department of motor vehicles, are an example of a traffic law in which the sanction rapidly follows the offense. The power of ALR laws has been attributed to how swiftly the sanction is applied, but does the length of suspension matter? Our objectives were to (a) determine the relationship of the ALR suspension length to the prevalence of drinking drivers relative to sober drivers in fatal crashes and (b) estimate the extent to which the relationship is associated to the general deterrent effect compared to the specific deterrent effect of the law. Data comparing the impact of ALR law implementation and ALR law suspension periods were analyzed using structural equation modeling techniques on the ratio of drinking drivers to nondrinking drivers in fatal crashes from the Fatality Analysis Reporting System (FARS). States with an ALR law with a short suspension period (1-30 days) had a significantly lower drinking driver ratio than states with no ALR law. States with a suspension period of 91-180 days had significantly lower ratios than states with shorter suspension periods, while the three states with suspension lengths of 181 days or longer had significantly lower ratios than states with shorter suspension periods. The implementation of any ALR law was associated with a 13.1% decrease in the drinking/nondrinking driver fatal crash ratio but only a 1.8% decrease in the intoxicated/nonintoxicated fatal crash ratio. The ALR laws and suspension lengths had a significant general deterrent effect, but no specific deterrent effect. States might want to keep (or adopt) ALR laws for their general deterrent effects and pursue alternatives for specific deterrent effects. States with short ALR suspension periods should consider lengthening them to 91 days or longer.

  5. Volume reconstruction optimization for tomo-PIV algorithms applied to experimental data

    Science.gov (United States)

    Martins, Fabio J. W. A.; Foucaut, Jean-Marc; Thomas, Lionel; Azevedo, Luis F. A.; Stanislas, Michel

    2015-08-01

    Tomographic PIV is a three-component volumetric velocity measurement technique based on the tomographic reconstruction of a particle distribution imaged by multiple camera views. In essence, the performance and accuracy of this technique is highly dependent on the parametric adjustment and the reconstruction algorithm used. Although synthetic data have been widely employed to optimize experiments, the resulting reconstructed volumes might not have optimal quality. The purpose of the present study is to offer quality indicators that can be applied to data samples in order to improve the quality of velocity results obtained by the tomo-PIV technique. The methodology proposed can potentially lead to significantly reduction in the time required to optimize a tomo-PIV reconstruction, also leading to better quality velocity results. Tomo-PIV data provided by a six-camera turbulent boundary-layer experiment were used to optimize the reconstruction algorithms according to this methodology. Velocity statistics measurements obtained by optimized BIMART, SMART and MART algorithms were compared with hot-wire anemometer data and velocity measurement uncertainties were computed. Results indicated that BIMART and SMART algorithms produced reconstructed volumes with equivalent quality as the standard MART with the benefit of reduced computational time.

  6. Volume reconstruction optimization for tomo-PIV algorithms applied to experimental data

    International Nuclear Information System (INIS)

    Martins, Fabio J W A; Foucaut, Jean-Marc; Stanislas, Michel; Thomas, Lionel; Azevedo, Luis F A

    2015-01-01

    Tomographic PIV is a three-component volumetric velocity measurement technique based on the tomographic reconstruction of a particle distribution imaged by multiple camera views. In essence, the performance and accuracy of this technique is highly dependent on the parametric adjustment and the reconstruction algorithm used. Although synthetic data have been widely employed to optimize experiments, the resulting reconstructed volumes might not have optimal quality. The purpose of the present study is to offer quality indicators that can be applied to data samples in order to improve the quality of velocity results obtained by the tomo-PIV technique. The methodology proposed can potentially lead to significantly reduction in the time required to optimize a tomo-PIV reconstruction, also leading to better quality velocity results. Tomo-PIV data provided by a six-camera turbulent boundary-layer experiment were used to optimize the reconstruction algorithms according to this methodology. Velocity statistics measurements obtained by optimized BIMART, SMART and MART algorithms were compared with hot-wire anemometer data and velocity measurement uncertainties were computed. Results indicated that BIMART and SMART algorithms produced reconstructed volumes with equivalent quality as the standard MART with the benefit of reduced computational time. (paper)

  7. Comparison of the compressive yield response of aggregated suspensions: Pressure filtration, centrifugation, and osmotic consolidation

    International Nuclear Information System (INIS)

    Miller, K.T.; Melant, R.M.; Zukoski, C.F.

    1996-01-01

    The compressive rheological responses of suspensions containing flocculated kaolin, alumina (average particle sizes of 0.2 and 0.5 microm), and hydrous zirconia (average particle sizes of 8, 57, and 139 nm) particles have been measured using three different techniques: pressure filtration, volume fraction profile during centrifugation, and sediment height during centrifugation at multiple spinning speeds. While the volume fraction profile technique appears to be experimentally most robust, equivalent responses are found using the different techniques, indicating that the compressive yield stress is a material property of a given suspension. The compressive yield stress of each suspension increases rapidly with volume fraction but cannot be generally described using simple power-law or exponential fits. The compressive yield stress also increases with the inverse square of particle size. The packing behavior of the suspensions undergoing osmotic consolidation is compared with the mechanical compressive yield response. Some suspensions exhibited the same packing behavior as in the mechanical techniques, while others consistently packed to higher densities during osmotic consolidation. Although equivalent osmotic and mechanical loads do not always result in the same volume fractions, the similar increases in volume fraction with applied driving force suggest that both the osmotic and mechanical techniques are controlled by the force needed to rearrange the particle network

  8. Ensemble-average versus suspension-scale Cauchy continuum-mechanical definitions of stress in polarized suspensions: Global homogenization of a dilute suspension of dipolar spherical particles

    International Nuclear Information System (INIS)

    Almog, Y.; Brenner, H.

    1999-01-01

    The macroscale rheological properties of a dilute suspension exposed to a uniform external field and composed of identical, rigid, inhomogeneous, dipolar, spherical particles dispersed in an incompressible Newtonian fluid and possessing the same mean density as the latter fluid are derived from knowledge of its microscale properties by applying a global ensemble-averaging technique. Each dipole, which is permanently embedded in the particle, is assumed to be generated by the presence of an inhomogeneous external body-force field in the particle interior resulting from the action of the uniform external field on an inhomogeneous distribution of interior matter. It is shown that although the ensemble-average stress tensor is symmetric, the suspension nevertheless behaves macroscopically as if it possessed an asymmetric stress tensor. This seeming contradiction can be traced to the fact that the average body force acting on the contents of any arbitrarily drawn volume lying in the interior of the suspension does not vanish despite the fact that each particle is 'neutrally buoyant'. That this force is not zero stems from the fact that some particles necessarily straddle the closed surface bounding that volume, and that the distribution of external body forces over the interiors of these particles is nonuniform. As such, that portion of the spherical particle lying outside of the surface enclosing the domain exerts a force on the remaining portion of the sphere lying within that domain. We then demonstrate that the natural macroscopic model, which is derived by equating the divergence of the suspension-scale stress appearing in that model to the ensemble-average external body-force field, and which predicts a symmetric stress tensor, is macroscopically deficient with respect to the more intuitive asymmetric stress model usually proposed by continuum mechanicians for such a suspension. It is shown that the latter, continuum-mechanical model recovers all the physically

  9. EDITORIAL: Colloidal suspensions Colloidal suspensions

    Science.gov (United States)

    Petukhov, Andrei; Kegel, Willem; van Duijneveldt, Jeroen

    2011-05-01

    Special issue in honour of Henk Lekkerkerker's 65th birthday Professor Henk N W Lekkerkerker is a world-leading authority in the field of experimental and theoretical soft condensed matter. On the occasion of his 65th birthday in the summer of 2011, this special issue celebrates his many contributions to science. Henk Lekkerkerker obtained his undergraduate degree in chemistry at the University of Utrecht (1968) and moved to Calgary where he received his PhD in 1971. He moved to Brussels as a NATO fellow at the Université Libre de Bruxelles and was appointed to an assistant professorship (1974), an associate professorship (1977) and a full professorship (1980) in physical chemistry at the Vrije Universiteit Brussel. In 1985 he returned to The Netherlands to take up a professorship at the Van 't Hoff Laboratory, where he has been ever since. He has received a series of awards during his career, including the Onsager Medal (1999) of the University of Trondheim, the Bakhuys Roozeboom Gold Medal (2003) of the Royal Dutch Academy of Arts and Sciences (KNAW), the ECIS-Rhodia European Colloid and Interface Prize (2003), and the Liquid Matter Prize of the European Physical Society (2008). He was elected a member of KNAW in 1996, was awarded an Academy Chair position in 2005, and has held several visiting lectureships. Henk's work focuses on phase transitions in soft condensed matter, and he has made seminal contributions to both the theoretical and experimental aspects of this field. Here we highlight three major themes running through his work, and a few selected publications. So-called depletion interactions may lead to phase separation in colloid-polymer mixtures, and Henk realised that the partitioning of polymer needs to be taken into account to describe the phase behaviour correctly [1]. Colloidal suspensions can be used as model fluids, with the time- and length-scales involved leading to novel opportunities, notably the direct observation of capillary waves at a

  10. Linear viscoelastic properties of aging suspensions

    NARCIS (Netherlands)

    Purnomo, E.H.; Purnomo, E.H; van den Ende, Henricus T.M.; Mellema, J.; Mugele, Friedrich Gunther

    2006-01-01

    We have examined the linear viscoelastic behavior of poly-N-isopropylacrylamide (PNIPAM) microgel suspensions in order to obtain insight in the aging processes in these densely packed suspensions at various temperatures below the volume transition temperature. The system is found to display a strong

  11. Predicting biopharmaceutical performance of oral drug candidates - Extending the volume to dissolve applied dose concept.

    Science.gov (United States)

    Muenster, Uwe; Mueck, Wolfgang; van der Mey, Dorina; Schlemmer, Karl-Heinz; Greschat-Schade, Susanne; Haerter, Michael; Pelzetter, Christian; Pruemper, Christian; Verlage, Joerg; Göller, Andreas H; Ohm, Andreas

    2016-05-01

    The purpose of the study was to experimentally deduce pH-dependent critical volumes to dissolve applied dose (VDAD) that determine whether a drug candidate can be developed as immediate release (IR) tablet containing crystalline API, or if solubilization technology is needed to allow for sufficient oral bioavailability. pH-dependent VDADs of 22 and 83 compounds were plotted vs. the relative oral bioavailability (AUC solid vs. AUC solution formulation, Frel) in humans and rats, respectively. Furthermore, in order to investigate to what extent Frel rat may predict issues with solubility limited absorption in human, Frel rat was plotted vs. Frel human. Additionally, the impact of bile salts and lecithin on in vitro dissolution of poorly soluble compounds was tested and data compared to Frel rat and human. Respective in vitro - in vivo and in vivo - in vivo correlations were generated and used to build developability criteria. As a result, based on pH-dependent VDAD, Frel rat and in vitro dissolution in simulated intestinal fluid the IR formulation strategy within Pharmaceutical Research and Development organizations can be already set at late stage of drug discovery. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Inseminating dose and water volume applied to the artificial fertilization of Steindachneridion parahybae (Steindachner, 1877 (Siluriformes: Pimelodidae: Brazilian endangered fish

    Directory of Open Access Journals (Sweden)

    Eduardo Antônio Sanches

    Full Text Available Abstract The Steindachneridion parahybae is an endangered catfish from Brazil and strategies applied for gametes optimization are necessary. The aim of this study was to assess inseminating doses and water volume upon the fertilization, hatching rates and percentage of normal larvae in S. parahybae . Was used a randomized design in factorial scheme (4×4 with four inseminating doses: 1.0×104, 1.0×105, 1.0×106, 1.0×107spermatozoa oocyte-1 and four volumes of water: 1, 35, 65 and 95mL of water g-1 of oocytes. The combination of doses and volumes were performed in triplicates (n=48. Each incubator (1.5L of useful volume with 1g of oocytes was considered as an experimental unit. Significant interaction between inseminating doses and volumes of water to the values of the fertilization rates and quadratic effect of doses and volume for the values of hatching rates were observed. The doses and volumes did not influence the percentage of normal larvae (87.70±5.06%. It is recommended the use of 5.5×106 spermatozoa oocyte-1 and 1mL of water g-1 of oocytes during in vitro fertilization procedure. These results allowed us to develop new biotechnological strategies applied to the conservation of S. parahybae .

  13. Applying ARIMA model for annual volume time series of the Magdalena River

    Directory of Open Access Journals (Sweden)

    Gloria Amaris

    2017-04-01

    Conclusions: The simulated results obtained with the ARIMA model compared to the observed data showed a fairly good adjustment of the minimum and maximum magnitudes. This allows concluding that it is a good tool for estimating minimum and maximum volumes, even though this model is not capable of simulating the exact behaviour of an annual volume time series.

  14. Scale-up of hydrophobin-assisted recombinant protein production in tobacco BY-2 suspension cells.

    Science.gov (United States)

    Reuter, Lauri J; Bailey, Michael J; Joensuu, Jussi J; Ritala, Anneli

    2014-05-01

    Plant suspension cell cultures are emerging as an alternative to mammalian cells for production of complex recombinant proteins. Plant cell cultures provide low production cost, intrinsic safety and adherence to current regulations, but low yields and costly purification technology hinder their commercialization. Fungal hydrophobins have been utilized as fusion tags to improve yields and facilitate efficient low-cost purification by surfactant-based aqueous two-phase separation (ATPS) in plant, fungal and insect cells. In this work, we report the utilization of hydrophobin fusion technology in tobacco bright yellow 2 (BY-2) suspension cell platform and the establishment of pilot-scale propagation and downstream processing including first-step purification by ATPS. Green fluorescent protein-hydrophobin fusion (GFP-HFBI) induced the formation of protein bodies in tobacco suspension cells, thus encapsulating the fusion protein into discrete compartments. Cultivation of the BY-2 suspension cells was scaled up in standard stirred tank bioreactors up to 600 L production volume, with no apparent change in growth kinetics. Subsequently, ATPS was applied to selectively capture the GFP-HFBI product from crude cell lysate, resulting in threefold concentration, good purity and up to 60% recovery. The ATPS was scaled up to 20 L volume, without loss off efficiency. This study provides the first proof of concept for large-scale hydrophobin-assisted production of recombinant proteins in tobacco BY-2 cell suspensions. © 2013 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  15. A hybrid ARIMA and neural network model applied to forecast catch volumes of Selar crumenophthalmus

    Science.gov (United States)

    Aquino, Ronald L.; Alcantara, Nialle Loui Mar T.; Addawe, Rizavel C.

    2017-11-01

    The Selar crumenophthalmus with the English name big-eyed scad fish, locally known as matang-baka, is one of the fishes commonly caught along the waters of La Union, Philippines. The study deals with the forecasting of catch volumes of big-eyed scad fish for commercial consumption. The data used are quarterly caught volumes of big-eyed scad fish from 2002 to first quarter of 2017. This actual data is available from the open stat database published by the Philippine Statistics Authority (PSA)whose task is to collect, compiles, analyzes and publish information concerning different aspects of the Philippine setting. Autoregressive Integrated Moving Average (ARIMA) models, Artificial Neural Network (ANN) model and the Hybrid model consisting of ARIMA and ANN were developed to forecast catch volumes of big-eyed scad fish. Statistical errors such as Mean Absolute Errors (MAE) and Root Mean Square Errors (RMSE) were computed and compared to choose the most suitable model for forecasting the catch volume for the next few quarters. A comparison of the results of each model and corresponding statistical errors reveals that the hybrid model, ARIMA-ANN (2,1,2)(6:3:1), is the most suitable model to forecast the catch volumes of the big-eyed scad fish for the next few quarters.

  16. Applying of the NVIDIA CUDA to the video processing in the task of the roundwood volume estimation

    Directory of Open Access Journals (Sweden)

    Kruglov Artem

    2016-01-01

    Full Text Available The paper is devoted to the parallel computing. The algorithm for roundwood volume estimation had insufficient performance so it was decided to port its bottleneck part on the GPU. The analysis of various GPGPU techniques was observed and the NVIDIA CUDA technology was chosen for implementation. The results of the research have shown the high potential of the GPU implementation in the improvement performance of the computation. The speedup of the algorithm for the roundwood volume estimation is more than 300% after porting on GPU with implementation of the CUDA technology. This helps to apply the machine vision algorithm in real-time system.

  17. Magnetic separation from superparamagnetic particle suspensions

    International Nuclear Information System (INIS)

    Sinha, Ashok; Ganguly, Ranjan; Puri, Ishwar K.

    2009-01-01

    We investigate the magnetophoretic separation of magnetic microparticles from a non-dilute flow in a microfluidic channel and their subsequent field-induced aggregation under the influence of an externally applied magnetic force. This force induces dipolar interactions between the particles that aid in their separation from the flow. Existing analytical models for dilute suspensions cannot be extended to non-dilute suspensions in which interparticle magnetic interactions play an important role. We therefore conduct a parametric investigation of the mechanics of this problem in a microcapillary flow through simulations and experimental visualization. When a magnetic field is applied, the magnetic microparticles form an aggregate on the channel wall that is influenced by the competition between the holding magnetic force and the aggregate-depleting flow shear force. Microparticle collection in the aggregate increases linearly with increasing magnetic field strength and is characterized by distinct buildup and washaway phases. The collected microparticle volume fraction in an aggregate is found to depend on a single dimensional group that depends upon characteristic system parameters.

  18. 40 CFR 1045.635 - What special provisions apply for small-volume engine manufacturers?

    Science.gov (United States)

    2010-07-01

    ... provisions related to the transition to new emission standards. See § 1045.145. (2) More flexible arrangements for creating engine families for high-performance engines. See § 1045.230. (3) Assigned... small-volume engine manufacturer, we will work with you to determine a reasonable schedule for complying...

  19. Applying ARIMA model for annual volume time series of the Magdalena River

    OpenAIRE

    Gloria Amaris; Humberto Ávila; Thomas Guerrero

    2017-01-01

    Context: Climate change effects, human interventions, and river characteristics are factors that increase the risk on the population and the water resources. However, negative impacts such as flooding, and river droughts may be previously identified using appropriate numerical tools. Objectives: The annual volume (Millions of m3/year) time series of the Magdalena River was analyzed by an ARIMA model, using the historical time series of the Calamar station (Instituto de Hidrología, Meteoro...

  20. Osmotic consolidation of suspensions and gels

    International Nuclear Information System (INIS)

    Miller, K.T.; Zukoski, C.F.

    1994-01-01

    An osmotic method for the consolidation of suspensions of ceramic particles is demonstrated. Concentrated solutions of poly(ethylene oxide) are separated from a suspension of ceramic particles by a semipermeable membrane, creating a gradient in solvent chemical potential. Solvent passes from the suspension into the polymer solution, lowering its free energy and consolidating the suspension. Dispersions of stable 8-nm hydrous zirconia particles were consolidated to over 47% by volume. Suspensions of α-alumina in three states of aggregation (dispersed, weakly flocculated, and strongly flocculated) were consolidated to densities greater than or equal to those produced in conventional pressure filtration. Moreover, the as-consolidated alumina bodies were partially drained of fluid during the osmotic consolidation process, producing cohesive partially dried bodies with improved handling characteristics

  1. Machine vision for high-precision volume measurement applied to levitated containerless material processing

    International Nuclear Information System (INIS)

    Bradshaw, R.C.; Schmidt, D.P.; Rogers, J.R.; Kelton, K.F.; Hyers, R.W.

    2005-01-01

    By combining the best practices in optical dilatometry with numerical methods, a high-speed and high-precision technique has been developed to measure the volume of levitated, containerlessly processed samples with subpixel resolution. Containerless processing provides the ability to study highly reactive materials without the possibility of contamination affecting thermophysical properties. Levitation is a common technique used to isolate a sample as it is being processed. Noncontact optical measurement of thermophysical properties is very important as traditional measuring methods cannot be used. Modern, digitally recorded images require advanced numerical routines to recover the subpixel locations of sample edges and, in turn, produce high-precision measurements

  2. Microstructural Dynamics and Rheology of Suspensions of Rigid Fibers

    Science.gov (United States)

    Butler, Jason E.; Snook, Braden

    2018-01-01

    The dynamics and rheology of suspensions of rigid, non-Brownian fibers in Newtonian fluids are reviewed. Experiments, theories, and computer simulations are considered, with an emphasis on suspensions at semidilute and concentrated conditions. In these suspensions, interactions between the particles strongly influence the microstructure and rheological properties of the suspension. The interactions can arise from hydrodynamic disturbances, giving multibody interactions at long ranges and pairwise lubrication forces over short distances. For concentrated suspensions, additional interactions due to excluded volume (contacts) and adhesive forces are addressed. The relative importance of the various interactions as a function of fiber concentration is assessed.

  3. IMAGE information monitoring and applied graphics software environment. Volume 2. Software description

    International Nuclear Information System (INIS)

    Hallam, J.W.; Ng, K.B.; Upham, G.L.

    1986-09-01

    The EPRI Information Monitoring and Applied Graphics Environment (IMAGE) system is designed for 'fast proto-typing' of advanced concepts for computer-aided plant operations tools. It is a flexible software system which can be used for rapidly creating, dynamically driving and evaluating advanced operator aid displays. The software is written to be both host computer and graphic device independent

  4. Applying Technology to Unmet Needs. Technology and the American Economy, Appendix, Volume V.

    Science.gov (United States)

    National Commission on Technology, Automation and Economic Progress, Washington, DC.

    Twelve studies dealing with the problems of applying technology to unmet human and community needs are presented. "Urban Planning and Metropolitan Development--The Role of Technology," examines the possibilities of the computer and other modern planning tools. "Technology, Automation, and Economic Progress in Housing and Urban Development"…

  5. Automatic assessment of volume asymmetries applied to hip abductor muscles in patients with hip arthroplasty

    Science.gov (United States)

    Klemt, Christian; Modat, Marc; Pichat, Jonas; Cardoso, M. J.; Henckel, Joahnn; Hart, Alister; Ourselin, Sebastien

    2015-03-01

    Metal-on-metal (MoM) hip arthroplasties have been utilised over the last 15 years to restore hip function for 1.5 million patients worldwide. Althoug widely used, this hip arthroplasty releases metal wear debris which lead to muscle atrophy. The degree of muscle wastage differs across patients ranging from mild to severe. The longterm outcomes for patients with MoM hip arthroplasty are reduced for increasing degrees of muscle atrophy, highlighting the need to automatically segment pathological muscles. The automated segmentation of pathological soft tissues is challenging as these lack distinct boundaries and morphologically differ across subjects. As a result, there is no method reported in the literature which has been successfully applied to automatically segment pathological muscles. We propose the first automated framework to delineate severely atrophied muscles by applying a novel automated segmentation propagation framework to patients with MoM hip arthroplasty. The proposed algorithm was used to automatically quantify muscle wastage in these patients.

  6. Applied mechanics and mechatronics special topic volume with invited peer reviewed papers only

    CERN Document Server

    Trebuňa, František

    2014-01-01

    The issue ""Applied Mechanics and Mechatronics"" contains results of research from researchers and designers from several prominent universities and research institutes of Central Europe.The publication is divided into three following chapters: Modeling and Simulation of Mechanic and Mechatronic SystemsAnalysis and Design of Mechanic and Mechatronic SystemsExperimental methods in Mechanics and Mechatronics. The submitted publication provides insight on modern approaches and methods in designing, modeling and experimental analyzing of mechanic and mechatronics systems.

  7. Technical Note: Harmonic analysis applied to MR image distortion fields specific to arbitrarily shaped volumes.

    Science.gov (United States)

    Stanescu, T; Jaffray, D

    2018-05-25

    Magnetic resonance imaging is expected to play a more important role in radiation therapy given the recent developments in MR-guided technologies. MR images need to consistently show high spatial accuracy to facilitate RT specific tasks such as treatment planning and in-room guidance. The present study investigates a new harmonic analysis method for the characterization of complex 3D fields derived from MR images affected by system-related distortions. An interior Dirichlet problem based on solving the Laplace equation with boundary conditions (BCs) was formulated for the case of a 3D distortion field. The second-order boundary value problem (BVP) was solved using a finite elements method (FEM) for several quadratic geometries - i.e., sphere, cylinder, cuboid, D-shaped, and ellipsoid. To stress-test the method and generalize it, the BVP was also solved for more complex surfaces such as a Reuleaux 9-gon and the MR imaging volume of a scanner featuring a high degree of surface irregularities. The BCs were formatted from reference experimental data collected with a linearity phantom featuring a volumetric grid structure. The method was validated by comparing the harmonic analysis results with the corresponding experimental reference fields. The harmonic fields were found to be in good agreement with the baseline experimental data for all geometries investigated. In the case of quadratic domains, the percentage of sampling points with residual values larger than 1 mm were 0.5% and 0.2% for the axial components and vector magnitude, respectively. For the general case of a domain defined by the available MR imaging field of view, the reference data showed a peak distortion of about 12 mm and 79% of the sampling points carried a distortion magnitude larger than 1 mm (tolerance intrinsic to the experimental data). The upper limits of the residual values after comparison with the harmonic fields showed max and mean of 1.4 mm and 0.25 mm, respectively, with only 1.5% of

  8. Sensitivity and uncertainty analyses applied to criticality safety validation, methods development. Volume 1

    International Nuclear Information System (INIS)

    Broadhead, B.L.; Hopper, C.M.; Childs, R.L.; Parks, C.V.

    1999-01-01

    This report presents the application of sensitivity and uncertainty (S/U) analysis methodologies to the code/data validation tasks of a criticality safety computational study. Sensitivity and uncertainty analysis methods were first developed for application to fast reactor studies in the 1970s. This work has revitalized and updated the available S/U computational capabilities such that they can be used as prototypic modules of the SCALE code system, which contains criticality analysis tools currently used by criticality safety practitioners. After complete development, simplified tools are expected to be released for general use. The S/U methods that are presented in this volume are designed to provide a formal means of establishing the range (or area) of applicability for criticality safety data validation studies. The development of parameters that are analogous to the standard trending parameters forms the key to the technique. These parameters are the D parameters, which represent the differences by group of sensitivity profiles, and the ck parameters, which are the correlation coefficients for the calculational uncertainties between systems; each set of parameters gives information relative to the similarity between pairs of selected systems, e.g., a critical experiment and a specific real-world system (the application)

  9. APPLIED MECHANICS REVIEWS, WADEX WORD AND AUTHOR INDEX, VOLUME XVI, 1963,

    Science.gov (United States)

    Author inDEX ) an IBM 1401 prepared mechanical index, extension of KWIC. WADEX usable for browsing and searching. This second WADEX is based on 8,000 titles of APPLIED MECHANICS REVIEWS (AMR), Vol. 16, 1963, an international critical review magazine. In WADEX, titles printed fully with author names, and as many lines used as necessary (60 characters per line). WADEX entry: word in title (except forbidden word) or author’s name. Alphabetically sequenced entries printed out of context. Words are single words or hypenated word pairs or ’Tagged Words’ (TW).

  10. Self-powered suspension criterion and energy regeneration implementation scheme of motor-driven active suspension

    Science.gov (United States)

    Yan, Shuai; Sun, Weichao

    2017-09-01

    Active suspension systems have advantages on mitigating the effects of vehicle vibration caused by road roughness, which are one of the most important component parts in influencing the performances of vehicles. However, high amount of energy consumption restricts the application of active suspension systems. From the point of energy saving, this paper presents a self-powered criterion of the active suspension system to judge whether a motor-driven suspension can be self-powered or not, and then a motor parameter condition is developed as a reference to design a self-powered suspension. An energy regeneration implementation scheme is subsequently proposed to make the active suspension which has the potential to be self-powered achieve energy-saving target in the real application. In this implementation scheme, operating electric circuits are designed based on different working status of the actuator and power source and it is realizable to accumulate energy from road vibration and supply energy to the actuator by switching corresponding electric circuits. To apply the self-powered suspension criterion and energy regeneration implementation scheme, an active suspension system is designed with a constrained H∞ controller and calculation results indicate that it has the capability to be self-powered. Simulation results show that the performances of the self-powered active suspension are nearly the same as those of the active suspension with an external energy source and can achieve energy regeneration at the same time.

  11. Decoupling Suspension Controller Based on Magnetic Flux Feedback

    Directory of Open Access Journals (Sweden)

    Wenqing Zhang

    2013-01-01

    Full Text Available The suspension module control system model has been established based on MIMO (multiple input and multiple output state feedback linearization. We have completed decoupling between double suspension points, and the new decoupling method has been applied to CMS04 magnetic suspension vehicle in national mid-low-speed maglev experiment field of Tangshan city in China. Double suspension system model is very accurate for investigating stability property of maglev control system. When magnetic flux signal is taken back to the suspension control system, the suspension module’s antijamming capacity for resisting suspension load variety has been proved. Also, the external force interference has been enhanced. As a result, the robustness and stability properties of double-electromagnet suspension control system have been enhanced.

  12. On the Benefits of Semi-Active Suspensions with Inerters

    Directory of Open Access Journals (Sweden)

    Xin-Jie Zhang

    2012-01-01

    Full Text Available Inerters have become a hot topic in recent years especially in vehicle, train, building suspension systems, etc. Eight different layouts of suspensions were analyzed with a quarter-car model in this paper. Dimensionless root mean square (RMS responses of the sprung mass vertical acceleration, the suspension travel, and the tire deflection are derived which were used to evaluate the performance of the quarter-car model. The behaviour of semi-active suspensions with inerters using Groundhook, Skyhook, and Hybrid control has been evaluated and compared to the performance of passive suspensions with inerters. Sensitivity analysis was applied to the development of a high performance semi-active suspension with an inerter. Numerical simulations indicate that a semi-active suspension with an inerter has much better performance than the passive suspension with an inerter, especially with the Hybrid control method, which has the best compromise between comfort and road holding quality.

  13. Decoupling suspension controller based on magnetic flux feedback.

    Science.gov (United States)

    Zhang, Wenqing; Li, Jie; Zhang, Kun; Cui, Peng

    2013-01-01

    The suspension module control system model has been established based on MIMO (multiple input and multiple output) state feedback linearization. We have completed decoupling between double suspension points, and the new decoupling method has been applied to CMS04 magnetic suspension vehicle in national mid-low-speed maglev experiment field of Tangshan city in China. Double suspension system model is very accurate for investigating stability property of maglev control system. When magnetic flux signal is taken back to the suspension control system, the suspension module's antijamming capacity for resisting suspension load variety has been proved. Also, the external force interference has been enhanced. As a result, the robustness and stability properties of double-electromagnet suspension control system have been enhanced.

  14. Effective viscous flow properties for fiber suspensions under concentrated conditions

    International Nuclear Information System (INIS)

    Christensen, R.M.

    1993-01-01

    The effective longitudinal and transverse shear viscosities are derived for an aligned fiber suspension. The solutions are valid under very concentrated conditions for a hexagonal arrangement of the single size fibers. The results compliment the classical dilute suspension forms at the other extreme of concentration. Empirical forms are constructed to cover the full range of volume fraction of the fiber phase. Also, single size spherical particle suspensions are given a similar treatment to that of the fiber case

  15. Formulation and Validation of an Efficient Computational Model for a Dilute, Settling Suspension Undergoing Rotational Mixing

    Energy Technology Data Exchange (ETDEWEB)

    Sprague, Michael A.; Stickel, Jonathan J.; Sitaraman, Hariswaran; Crawford, Nathan C.; Fischer, Paul F.

    2017-04-11

    Designing processing equipment for the mixing of settling suspensions is a challenging problem. Achieving low-cost mixing is especially difficult for the application of slowly reacting suspended solids because the cost of impeller power consumption becomes quite high due to the long reaction times (batch mode) or due to large-volume reactors (continuous mode). Further, the usual scale-up metrics for mixing, e.g., constant tip speed and constant power per volume, do not apply well for mixing of suspensions. As an alternative, computational fluid dynamics (CFD) can be useful for analyzing mixing at multiple scales and determining appropriate mixer designs and operating parameters. We developed a mixture model to describe the hydrodynamics of a settling cellulose suspension. The suspension motion is represented as a single velocity field in a computationally efficient Eulerian framework. The solids are represented by a scalar volume-fraction field that undergoes transport due to particle diffusion, settling, fluid advection, and shear stress. A settling model and a viscosity model, both functions of volume fraction, were selected to fit experimental settling and viscosity data, respectively. Simulations were performed with the open-source Nek5000 CFD program, which is based on the high-order spectral-finite-element method. Simulations were performed for the cellulose suspension undergoing mixing in a laboratory-scale vane mixer. The settled-bed heights predicted by the simulations were in semi-quantitative agreement with experimental observations. Further, the simulation results were in quantitative agreement with experimentally obtained torque and mixing-rate data, including a characteristic torque bifurcation. In future work, we plan to couple this CFD model with a reaction-kinetics model for the enzymatic digestion of cellulose, allowing us to predict enzymatic digestion performance for various mixing intensities and novel reactor designs.

  16. 40 CFR 80.595 - How does a small or GPA refiner apply for a motor vehicle diesel fuel volume baseline for the...

    Science.gov (United States)

    2010-07-01

    ... for a motor vehicle diesel fuel volume baseline for the purpose of extending their gasoline sulfur... PROGRAMS (CONTINUED) REGULATION OF FUELS AND FUEL ADDITIVES Motor Vehicle Diesel Fuel; Nonroad, Locomotive... a small or GPA refiner apply for a motor vehicle diesel fuel volume baseline for the purpose of...

  17. Naratriptan hydrochloride in extemporaneosly compounded oral suspensions.

    Science.gov (United States)

    Zhang, Y P; Trissel, L A; Fox, J L

    2000-01-01

    The purpose of this study was to determine the pharmaceutical acceptability and chemical stability of naratriptan hydrochloride in three extemporaneously compounded suspension formulations. The naratriptan-hydrochloride oral suspensions were prepared from 2.5-mg commercial tablets yielding a nominal naratriptan concentration of 0.5 mg/mL. The suspension vehicles selected for testing were Syrpalta, an equal-parts mixture of Ora-Plus and Ora-Sweet, and an equal-parts mixture of Ora-Plus and Ora-Sweet SF. The tablets were crushed and thoroughly triturated to a fine powder using a porcelain mortar and pestle. The powder was incorporated into a portion of the Syrpalta or Ora-Plus suspension vehicle and mixed until homogeneous. The mixtures were then brought to volume with Syrpalta, Ora-Sweet or Ora-Sweet SF, as appropriate. The suspensions were packaged in amber, plastic, screw-cap prescription bottles and stored at 23 deg C for seven days and 4 deg C for 90 days. An adequate suspension was never achieved in Syrpalta. The crushed-tablet powder did not produce a uniformly dispersed mixture and exhibited clumping and a high rate of sedimentation. A distinct layer of the solid tablet material settled immediately after shaking. Over the next four hours, a densely packed, yellow, caked layer formed at the bottom of the containers, making resuspension difficult. During storage, the caking became worse. Chemical analysis was not performed. The Ora-Plus and Ora-Sweet or Ora-Sweet SF suspensions had a slight greenish cast and were resuspended without difficulty by shaking for approximately ten seconds, yielding easily poured and homogeneous mixtures throughout the study. Visible settling and layering did not begin for four hours with the Ora-Sweet suspension and 24 hours for the Ora-Sweet SF suspension. High pressure liquid chromatographic analysis found that the naratriptan concentration in both suspension-vehicle combinations exhibited little or no loss for seven days at 23

  18. Numerical study of suspensions of deformable particles.

    Science.gov (United States)

    Brandt, Luca; Rosti, Marco Edoardo

    2017-11-01

    We consider a model non-Newtonian fluid consisting of a suspension of deformable particles in a Newtonian solvent. Einstein showed in his pioneering work that the relative increase in effective viscosity is a linear function of the particle volume fraction for dilute suspensions of rigid particles. Inertia has been shown to introduce deviations from the behaviour predicted by the different empirical fits, an effect that can be related to an increase of the effective volume fraction. We here focus on the effect of elasticity, i.e. visco-elastic deformable particles. To tackle the problem at hand, we perform three-dimensional Direct Numerical Simulation of a plane Couette flow with a suspension of neutrally buoyant deformable viscous hyper-elastic particles. We show that elasticity produces a shear-thinning effect in elastic suspensions (in comparison to rigid ones) and that it can be understood in terms of a reduction of the effective volume fraction of the suspension. The deformation modifies the particle motion reducing the level of mutual interaction. Normal stress differences will also be considered. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

  19. Suspension trauma; Le traumatisme de suspension

    Energy Technology Data Exchange (ETDEWEB)

    Trudel, S. [Le Centre de sante et de services sociaux du rocher Perce, Chandler, PQ (Canada)

    2010-07-01

    This presentation discussed the precautions that should be taken to avoid falls from wind turbines or transmission towers. Suspension trauma was explained by a medical doctor in terms of physiology and the body's normal circulation and the elements that disturb normal physiology when in suspension. The trauma occurs following a fall, which carries the risk of 1or more disorders, such as massive hemorrhage, high cardiac pulse, and constriction of blood vessels. Nausea, vertigo, cardiac arrhythmia and sweating occur 15 to 20 minutes following the fall. The presentation emphasized the importance of having qualified personnel at the site and wearing proper harnesses and equipment that supports the neck. figs.

  20. Heat and mass transfer in particulate suspensions

    CERN Document Server

    Michaelides, Efstathios E (Stathis)

    2013-01-01

    Heat and Mass Transfer in Particulate Suspensions is a critical review of the subject of heat and mass transfer related to particulate Suspensions, which include both fluid-particles and fluid-droplet Suspensions. Fundamentals, recent advances and industrial applications are examined. The subject of particulate heat and mass transfer is currently driven by two significant applications: energy transformations –primarily combustion – and heat transfer equipment. The first includes particle and droplet combustion processes in engineering Suspensions as diverse as the Fluidized Bed Reactors (FBR’s) and Internal Combustion Engines (ICE’s). On the heat transfer side, cooling with nanofluids, which include nanoparticles, has attracted a great deal of attention in the last decade both from the fundamental and the applied side and has produced several scientific publications. A monograph that combines the fundamentals of heat transfer with particulates as well as the modern applications of the subject would be...

  1. Sintering of Fine Particles in Suspension Plasma Sprayed Coatings

    Directory of Open Access Journals (Sweden)

    Leszek Latka

    2010-07-01

    Full Text Available Suspension plasma spraying is a process that enables the production of finely grained nanometric or submicrometric coatings. The suspensions are formulated with the use of fine powder particles in water or alcohol with some additives. Subsequently, the suspension is injected into plasma jet and the liquid additives evaporate. The remaining fine solids are molten and subsequently agglomerate or remain solid, depending on their trajectory in the plasma jet. The coating’s microstructure results from these two groups of particles arriving on a substrate or previously deposited coating. Previous experimental studies carried out for plasma sprayed titanium oxide and hydroxyapatite coatings enabled us to observe either a finely grained microstructure or, when a different suspension injection mode was used, to distinguish two zones in the microstructure. These two zones correspond to the dense zone formed from well molten particles, and the agglomerated zone formed from fine solid particles that arrive on the substrate in a solid state. The present paper focuses on the experimental and theoretical analysis of the formation process of the agglomerated zone. The experimental section establishes the heat flux supplied to the coating during deposition. In order to achieve this, calorimetric measurements were made by applying experimental conditions simulating the real coatings’ growth. The heat flux was measured to be in the range from 0.08 to 0.5 MW/m2,depending on the experimental conditions. The theoretical section analyzes the sintering during the coating’s growth, which concerns the fine particles arriving on the substrate in the solid state. The models of volume, grain boundary and surface diffusion were analyzed and adapted to the size and chemistry of the grains, temperature and time scales corresponding to the suspension plasma spraying conditions. The model of surface diffusion was found to best describe the sintering during suspension

  2. Applied superconductivity

    CERN Document Server

    Newhouse, Vernon L

    1975-01-01

    Applied Superconductivity, Volume II, is part of a two-volume series on applied superconductivity. The first volume dealt with electronic applications and radiation detection, and contains a chapter on liquid helium refrigeration. The present volume discusses magnets, electromechanical applications, accelerators, and microwave and rf devices. The book opens with a chapter on high-field superconducting magnets, covering applications and magnet design. Subsequent chapters discuss superconductive machinery such as superconductive bearings and motors; rf superconducting devices; and future prospec

  3. Performance analysis of the FDTD method applied to holographic volume gratings: Multi-core CPU versus GPU computing

    Science.gov (United States)

    Francés, J.; Bleda, S.; Neipp, C.; Márquez, A.; Pascual, I.; Beléndez, A.

    2013-03-01

    The finite-difference time-domain method (FDTD) allows electromagnetic field distribution analysis as a function of time and space. The method is applied to analyze holographic volume gratings (HVGs) for the near-field distribution at optical wavelengths. Usually, this application requires the simulation of wide areas, which implies more memory and time processing. In this work, we propose a specific implementation of the FDTD method including several add-ons for a precise simulation of optical diffractive elements. Values in the near-field region are computed considering the illumination of the grating by means of a plane wave for different angles of incidence and including absorbing boundaries as well. We compare the results obtained by FDTD with those obtained using a matrix method (MM) applied to diffraction gratings. In addition, we have developed two optimized versions of the algorithm, for both CPU and GPU, in order to analyze the improvement of using the new NVIDIA Fermi GPU architecture versus highly tuned multi-core CPU as a function of the size simulation. In particular, the optimized CPU implementation takes advantage of the arithmetic and data transfer streaming SIMD (single instruction multiple data) extensions (SSE) included explicitly in the code and also of multi-threading by means of OpenMP directives. A good agreement between the results obtained using both FDTD and MM methods is obtained, thus validating our methodology. Moreover, the performance of the GPU is compared to the SSE+OpenMP CPU implementation, and it is quantitatively determined that a highly optimized CPU program can be competitive for a wider range of simulation sizes, whereas GPU computing becomes more powerful for large-scale simulations.

  4. Equivalent Air Spring Suspension Model for Quarter-Passive Model of Passenger Vehicles

    OpenAIRE

    Abid, Haider J.; Chen, Jie; Nassar, Ameen A.

    2015-01-01

    This paper investigates the GENSIS air spring suspension system equivalence to a passive suspension system. The SIMULINK simulation together with the OptiY optimization is used to obtain the air spring suspension model equivalent to passive suspension system, where the car body response difference from both systems with the same road profile inputs is used as the objective function for optimization (OptiY program). The parameters of air spring system such as initial pressure, volume of bag, l...

  5. HEPATOPROTECTIVE ACTION OF THYMALINUM AND SUSPENSION OF RED BONE MARROW IN TREATING EXPERIMENTAL TOXIC HEPATITIS OF RATS

    Directory of Open Access Journals (Sweden)

    E. F. Kulbekov

    2014-01-01

    Full Text Available Hepatic decompensation problems make it timely to search for the methods of its treatment. Stem cells usage in attempt to restore structures of organs and tissues is a promising direction of researches. However the problem of possible blast-cell transformation slows down studies in this direction. Attempt of thymalinum use as an antitumoral immune system's modulator may be successful and may widen the possibilities of stem cells use in hepatology. On the basis of toxical affection of rats' lever by tetrachloromethane and paracetamol we have studied hepatoprotective activity of thymalinum and suspension of rats' red bone marrow (RBM and a thymalinum + suspension of RBM complex. Hepatoprotective action was estimated by the volume of discharged bile of control group rats which received paracetamol comparing with intact animals. This confirms the absence of reliable hepatotoxical action of paracetamol following the methodology applied. Significant reduction of discharged bile volume of control group rats which received tetrachloromethane comparing with intact animals confirms the successfulness of the formation method of hepatitis model in animals which received tetrachloromethane. The animals which were given tetrachloromethane and thymalinum + suspension of RBM combination had bigger volume of bile discharged than control group animals. Hepatoprotective action tendency of thymalinum + suspension of RBM combination shown before on mice is also true for rats. 

  6. Aqueous suspensions of natural swelling clay minerals. 2. Rheological characterization.

    Science.gov (United States)

    Paineau, Erwan; Michot, Laurent J; Bihannic, Isabelle; Baravian, Christophe

    2011-06-21

    We report in this article a comprehensive investigation of the viscoelastic behavior of different natural colloidal clay minerals in aqueous solution. Rheological experiments were carried out under both dynamic and steady-state conditions, allowing us to derive the elasticity and yield stress. Both parameters can be renormalized for all sizes, ionic strength, and type of clay using in a first approach only the volume of the particles. However, applying such a treatment to various clays of similar shapes and sizes yields differences that can be linked to the repulsion strength and charge location in the swelling clays. The stronger the repulsive interactions, the better the orientation of clay particles in flows. In addition, a master linear relationship between the elasticity and yield stress whose value corresponds to a critical deformation of 0.1 was evidenced. Such a relationship may be general for any colloidal suspension of anisometric particles as revealed by the analysis of various experimental data obtained on either disk-shaped or lath- and rod-shaped particles. The particle size dependence of the sol-gel transition was also investigated in detail. To understand why suspensions of larger particles gel at a higher volume fraction, we propose a very simplified view based on the statistical hydrodynamic trapping of a particle by an another one in its neighborhood upon translation and during a short period of time. We show that the key parameter describing this hydrodynamic trapping varies as the cube of the average diameter and captures most features of the sol-gel transition. Finally, we pointed out that in the high shear limit the suspension viscosity is still closely related to electrostatic interactions and follows the same trends as the viscoelastic properties. © 2011 American Chemical Society

  7. Chain Dynamics in Magnetorheological Suspensions

    Science.gov (United States)

    Gast, A. P.; Furst, E. M.

    1999-01-01

    fluctuating chains of dipolar particles. Resolving this issue would contribute greatly to the understanding of these interesting and important materials. We have begun to test the predictions of the HT model by both examining the dynamics of individual chains and by measuring the forces between dipolar chains directly to accurately and quantitatively assess the interactions that they experience. To do so, we employ optical trapping techniques and video-microscopy to manipulate and observe our samples on the microscopic level. With these techniques, it is possible to observe chains that are fluctuating freely in three-dimensions, independent of interfacial effects. More importantly, we are able to controllably observe the interactions of two chains at various separations to measure the force-distance profile. The techniques also allow us to study the mechanical properties of individual chains and chain clusters. Our work to this point has focused on reversibly-formed dipolar chains due to field induced dipoles where the combination of this chaining, the dipolar forces, and the hydrodynamic interactions that dictate the rheology of the suspensions. One can envision, however, many situations where optical, electronic, or rheological behavior may be optimized with magneto-responsive anisotropic particles. Chains of polarizable particles may have the best properties as they can coil and flex in the absence of a field and stiffen and orient when a field is applied. We have recently demonstrated a synthesis of stable, permanent paramagnetic chains by both covalently and physically linking paramagnetic colloidal particles. The method employed allows us to create monodisperse chains of controlled length. We observed the stability, field-alignment, and rigidity of this new class of materials. The chains may exhibit unique rheological properties in an applied magnetic field over isotropic suspensions of paramagnetic particles. They are also useful rheological models as bead

  8. Rheology of organoclay suspension

    CSIR Research Space (South Africa)

    Hato, MJ

    2011-05-01

    Full Text Available The authors have studied the rheological properties of clay suspensions in silicone oil, where clay surfaces were modified with three different types of surfactants. Dynamic oscillation measurements showed a plateau-like behavior for all...

  9. Hydropneumatic suspension systems

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Wolfgang

    2011-07-01

    Hydropneumatic suspensions systems combine the excellent properties of gas springs with the favourable damping properties of hydraulic fluids. The advantages of these systems are particularly appropriate for automotive applications, such as passenger cars, trucks and agricultural equipment. In this book, Dr. Bauer provides an extensive overview of hydropneumatic suspension systems. Starting with a comparison of different types of suspension systems, the author subsequently describes the theoretical background associated with spring and damping characteristics of hydropneumatic systems and furthermore explains the design of the most important system components. Additionally he gives an overview of level control systems and various special functions. Finally the technology is illustrated by design examples and the outlook for future hydropneumatic suspensions is discussed. (orig.)

  10. Suspension Trauma / Orthostatic Intolerance

    Science.gov (United States)

    ... Suspension Trauma/Orthostatic Intolerance Safety and Health Information Bulletin SHIB 03-24-2004, updated 2011 This Safety ... the harness, the environmental conditions, and the worker's psychological state all may increase the onset and severity ...

  11. The Mystical Suspension

    Directory of Open Access Journals (Sweden)

    Héctor Santiesteban Oliva

    2016-11-01

    Full Text Available Mistical suspension, silence, time, absolute, ontology, ineffability, aletheiaIn the mystical ecstasy there is a sensorial and intellectual suspension when contemplating the absolute, the ontological Being. Silence is not only significant: it is revealing. The greatest expression of experience inner silence . The word is insufficient when the ontological reality is revealed. Revelation or truth , the Greek concept of aletheia, takes on greater significance in that transcendental experience. It is also suspended phenomenological time and remains eternity open.

  12. Rheological Properties of Aqueous Nanometric Alumina Suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Chuanping [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    Colloidal processing is an effective and reliable approach in the fabrication of the advanced ceramic products. Successful colloidal processing of fine ceramic powders requires accurate control of the rheological properties. The accurate control relies on the understanding the influences of various colloidal parameters on the rheological properties. Almost all research done on the rheology paid less attention to the interactions of particle and solvent. However, the interactions of the particles are usually built up through the media in which the particles are suspended. Therefore, interactions of the particle with the media, the adsorbed layers on the particle surface, and chemical and physical properties of media themselves must influence the rheology of the suspension, especially for the dense suspensions containing nanosized particles. Relatively little research work has been reported in this area. This thesis addresses the rheological properties of nanometric alumina aqueous suspensions, and paying more attention to the interactions between particle and solvent, which in turn influence the particle-particle interactions. Dense nanometric alumina aqueous suspensions with low viscosity were achieved by environmentally-benign fructose additives. The rheology of nanometric alumina aqueous suspensions and its variation with the particle volume fraction and concentration of fructose were explored by rheometry. The adsorptions of solute (fructose) and solvent (water) on the nanometric alumina particle surfaces were measured and analyzed by TG/DSC, TOC, and NMR techniques. The mobility of water molecules in the suspensions and its variation with particle volume fractions and fructose additive were determined by the 17O NMR relaxation method. The interactions between the nanometric alumina particles in water and fructose solutions were investigated by AFM. The results indicated that a large number of water layers were physically bound on the particles

  13. Characterization of alumina suspensions by electroacoustics

    Energy Technology Data Exchange (ETDEWEB)

    Galassi, C.; Roncari, E.; Greenwood, R.; Piancastelli, A. [CNR, Faenza (Italy). Research Inst. for Ceramics Technology

    1997-12-31

    Using the acoustophoresis technique three different dispersants were selected to investigate the effect of the volume fraction of the suspension on the minimum amount of dispersant required to give the maximum zeta potential. No effect was detected over a volume fraction range 0.11 to 0.35. The acoustosizer was used to screen many dispersants for alumina in a relatively short time. From the viewpoint that the most stable suspensions are those with the greatest zeta potentials, then the following dispersants can be recommended: Reotan LA (0.25 mg/m{sup 2}) Dolapix CA (0.20 mg/m{sup 2}) and Dolapix PC33 (0.30 mg/m{sup 2}). Vanisperse and Borresperse are poor. Polyacrylic acid and polymethacrylic acid were better than some commercially available products. (orig.) 2 refs.

  14. RMN du deutérium sur des suspensions. Application à une boue de forage. Etude en température et en fréquence d'une argile à grands feuillets Deuterium Nmr on Suspensions Applied to Drilling Mud. a Temperature and Frequency Study of Large Stratum Shale

    Directory of Open Access Journals (Sweden)

    Letellier M.

    2006-12-01

    Full Text Available La mesure du temps de relaxation transversal T1 en fonction de la concentration permet de déterminer la surface hydrophile mouillée d'une suspension, à condition de connaître le T1 de surface. De même, la mesure de T1 en fonction du temps permet de déterminer les variations de surface lors d'une réaction lente telle que la prise d'une boue de forage, simulée par un mélange bentonite/ciment/eau lourde. L'avantage d'utiliser la résonance du deutérium est que sa relaxation dépend peu de la présence d'impuretés paramagnétiques ou de l'existence de mouvements moléculaires dans des espaces confinés, comme il est montré sur une argile à grands feuillets, la montmorillonite. Celle-ci est étudiée en fonction de la température, ce qui permet de mesurer, sans modifier la suspension, le T1 de surface. Measuring transverse T1 relaxation times as a function of concentration provides a determination of the hydrophilic surface, wetted with a suspension, as long as the surface relaxation T1 is known. Likewise, measuring T1 over time provides a determination of the surface variations during a slow reaction such as when drilling mud sets, which is simulated by a mixture of bentonite, cement and heavy water. Deuterium resonance measurements have the advantage that the relaxation depends little on the presence of paramagnetic impurities or molecular motion in a confined space, which has been demonstrated using a large stratum shale, montmorillonite. This shale has been studied as a function of temperature, which makes it possible to measure the surface relaxation T1 without modifying the suspension.

  15. Unifying Suspension and Granular flows near Jamming

    Directory of Open Access Journals (Sweden)

    DeGiuli Eric

    2017-01-01

    Full Text Available Rheological properties of dense flows of hard particles are singular as one approaches the jamming threshold where flow ceases, both for granular flows dominated by inertia, and for over-damped suspensions. Concomitantly, the lengthscale characterizing velocity correlations appears to diverge at jamming. Here we review a theoretical framework that gives a scaling description of stationary flows of frictionless particles. Our analysis applies both to suspensions and inertial flows of hard particles. We report numerical results in support of the theory, and show the phase diagram that results when friction is added, delineating the regime of validity of the frictionless theory.

  16. Gravity Drainage Kinetics of Papermaking Fibrous Suspensions

    Directory of Open Access Journals (Sweden)

    Przybysz Piotr

    2014-12-01

    Full Text Available The study analyses application possibilities of filtration and thickening models in evaluation of papermaking suspension drainage rate. The authors proposed their own method to estimate the drainage rate on the basis of an existing Ergun capillary model of liquid flow through a granular material. The proposed model was less sensitive to porosity changes than the Ergun model. An empirical verification proved robustness of the proposed approach. Taking into account discrepancies in the published data concerning how the drainage velocity of papermaking suspension is defined, this study examines which of the commonly applied models matches experimental results the best.

  17. Clogging in constricted suspension flows

    Science.gov (United States)

    Marin, Alvaro; Lhuissier, Henri; Rossi, Massimiliano; Kähler, Christian J.

    2018-02-01

    The flow of a charged-stabilized suspension through a single constricted channel is studied experimentally by tracking the particles individually. Surprisingly, the behavior is found to be qualitatively similar to that of inertial dry granular systems: For small values of the neck-to-particle size ratio (D /d reported for granular systems and agree for moderate particle volume fraction (ϕ ≈20 % ) with a simple stochastic model for the number of particles at the neck. For larger neck sizes (D /d >3 ), even at the largest ϕ (≈60 %) achievable in the experiments, an uninterrupted particle flow is observed, which resembles that of an hourglass. This particularly small value of D /d (≃3 ) at the transition to a practically uninterrupted flow is attributed to the low effective friction between the particles, achieved by the particle's functionalization and lubrication.

  18. Constitutive modeling of the rheological behavior of platelet suspensions

    Science.gov (United States)

    Sommer, Drew E.

    Compression molding of chopped fiber composites is used to manufacture complex 3D geometries with high fiber volume fractions of 50-60% and long, discontinuous fibers and thermoplastic matrices. When prepreg, chopped into platelets, is used as a charge material, the individual platelets remain intact during the molding process and flow relative to one another, as experimental observations show. Heterogeneity of the platelet/resin suspension cannot be considered at the structural scale of molding simulation. Instead, the suspension should be idealized into the homogenized anisotropic and viscous system which obeys the prescribed anisotropic stress-strain rate constitutive relation. The viscosity tensor of the aforementioned constitutive law was analytically evaluated in this work through the representative volume element (RVE) based analysis. An idealized microstructure of platelets was developed to perform such an analysis. The platelets were aligned and arranged in a planar configuration with periodic boundary conditions. Analytic expressions for the effective, anisotropic viscosities were derived by micromechanical analysis for the idealized microstructure of rigid platelets. In this analysis, the load transfer mechanisms and their contribution to the viscosity of the platelet assembly were investigated. The kinematic assumption of linear velocity distributions consistent with the mechanism of shearing rate was adopted. While the platelets were assumed to be rigid, the resin was taken as an incompressible, isotropic fluid which provided for the platelet-to-platelet load transfer. Strain rate and temperature dependence were included by modeling the polymer matrix as a Carreau fluid. Shear strain in the resin was developed due to the relative motion of adjacent platelets. The resin shear strain rate was expressed in terms of the corresponding platelet velocities. Equilibrium of the platelet was used to relate the applied far-field stress to the average strain rate

  19. Hybrid superconducting magnetic suspensions

    International Nuclear Information System (INIS)

    Tixador, P.; Hiebel, P.; Brunet, Y.; Chaud, X.; Gautier-Picard, P.

    1996-01-01

    Superconductors, especially high T c ones, are the most attractive materials to design stable and fully passive magnetic suspensions which have to control five degrees of freedom. The hybrid superconducting magnetic suspensions present high performances and a simple cooling mode. They consist of a permanent magnet bearing, stabilized by a suitable magnet-superconductor structure. Several designs are given and compared in terms of forces and stiffnesses. The design of the magnet bearing plays an important part. The superconducting magnetic bearing participates less in levitation but must provide a high stabilizing stiffness. This is achieved by the magnet configuration, a good material in term of critical current density and field cooling. A hybrid superconducting suspension for a flywheel is presented. This system consists of a magnet thrust bearing stabilized by superconductors interacting with an alternating polarity magnet structure. First tests and results are reported. Superconducting materials are magnetically melt-textured YBaCuO

  20. Evaluation of the AGCU Expressmarker 16 and 22 PCR Amplification Kits Using Biological Samples Applied to FTA Micro Cards in Reduced Volume Direct PCR Amplification Reactions

    Directory of Open Access Journals (Sweden)

    Samantha J Ogden

    2015-01-01

    Full Text Available This study evaluated the performance of the  Wuxi AGCU ScienTech Incorporation (HuiShan, Wuxi, China AGCU Expressmarker 16 (EX 16 and 22 (EX22 short tandem repeat (STR amplification kits in reduced reaction volumes using direct polymerase chain reaction (PCR amplification workflows. The commercially available PowerPlex® 21 (PP21 System (Promega, Wisconsin, USA, which follows similar direct workflows, was used as a reference. Anticoagulate blood applied to chemically impregnated  FTA TM Micro Cards (GE Healthcare UK Limited, Amersham Place, Little Chalfont, Buckinghamshire, HP7 9NA, UK was used to represent a complex biological sample. Allelic concordance, first-pass success rate, average peak heights, heterozygous peak height ratios (HPHRs, and intracolor and intercolor peak height balance were determined. In reduced volume PCR reactions, the performances of both the EX16 and EX22 STR amplification kits were comparable to that of the PP21 System. The level of performance was maintained at PCR reaction volumes, which are 40% of that recommended. The EX22 and PP21 System kits possess comparable overlapping genome coverage. This study evaluated the performance of the AGCU EX16 and EX22 STR amplification kits in reduced PCR reaction volumes using direct workflows in combination with whole blood applied to FTA TM Micro Cards. Allelic concordance, first-pass success rate, average peak heights, HPHRs, and intracolor and intercolor peak height balance were determined. A concordance analysis was completed that compared the performance of the EX16 and EX22 kits using human blood applied to FTA Micro Cards in combination with full, half, and reduced PCR reaction volumes. The PP21 System (Promega was used as a reference kit. Where appropriate, the distributions of data were assessed using the Shapiro-Wilk test. For normally-distributed data, statistics were calculated using analysis of variance (ANOVA and for nonparametric data the Wilcoxon

  1. Magnetic Suspension Technology Workshop

    International Nuclear Information System (INIS)

    Keckler, C.R.; Groom, N.J.; Britcher, C.P.

    1993-01-01

    In order to identify the state of magnetic suspension technology in such areas as rotating systems, pointing of experiments or subsystems, payload isolation, and superconducting materials, a workshop on Magnetic Suspension Technology was held at the Langley Research Center in Hampton, Virginia, on 2-4 Feb. 1988. The workshop included five technical sessions in which a total of 24 papers were presented. The technical sessions covered the areas of pointing, isolation, and measurement, rotating systems, modeling and control, and superconductors. A list of attendees is provided. Separate abstracts have been prepared for articles from this report

  2. Stability Prediction of Polymeric Suspensions of some Fluoroquinolones

    OpenAIRE

    Subhashree Sahoo; Chandra Kanti Chakraborti; Pradipta Kumar Behera

    2014-01-01

    Considering the importance of physical stability, zeta potential values, percentage volume of sedimentation and redispersibility of polymeric suspensions of some fluoroquinolones like Ciprofloxacin (Cipro) and Ofloxacin (Oflox) were measured. These formulations were prepared using two grades of Carbopol polymer such as C934 and C940; and Hydroxypropyl methylcellulose (HPMC). Above mentioned values of each suspension was determined by following standard methods. The results of those experiment...

  3. Effects of Angle Variations in Suspension Push-up Exercise.

    Science.gov (United States)

    Gulmez, Irfan

    2017-04-01

    Gulmez, I. Effects of angle variations in suspension push-up exercise. J Strength Cond Res 31(4): 1017-1023, 2017-This study aimed to determine and compare the amount of loads on the TRX Suspension Trainer (TRX) straps and ground reaction forces at 4 different angles during TRX push-ups. Twenty-eight male (mean age, 24.1 ± 2.9 years; height, 179.4 ± 8.0 m; weight, 78.8 ± 9.8 kg) physical education and sports university students participated in this study. The subjects were tested at TRX angles (0, 15, 30, 45°) during the TRX push-ups. Force data were recorded by a force platform and load cells integrated into the TRX straps. The results show that as the TRX angle was reduced, the load applied to the TRX straps increased and simultaneously the load measured by the force platform decreased. This was true for both the elbow joint changing from flexion to extension and vice versa. When the TRX angle was set at 0° and subjects' elbows were at extension during TRX push-up, 50.4% of the subjects' body weight, and when the elbows were at flexion, 75.3% of the body weight was registered by the sensors on the TRX straps. The results of this study can be used in the calculation of the training load and volume (resistance training programming) during TRX push-up exercises at varying angles.

  4. Electrorheological suspensions of laponite in oil: rheometry studies.

    Science.gov (United States)

    Parmar, K P S; Méheust, Y; Schjelderupsen, Børge; Fossum, J O

    2008-03-04

    We have studied the effect of an external direct current (DC) electric field ( approximately 1 kV/mm) on the rheological properties of colloidal suspensions consisting of aggregates of laponite particles in a silicone oil. Microscopy observations show that, under application of an electric field greater than a triggering electric field Ec approximately 0.6 kV/mm, laponite aggregates assemble into chain- and/or columnlike structures in the oil. Without an applied electric field, the steady-state shear behavior of such suspensions is Newtonian-like. Under application of an electric field larger than Ec, it changes dramatically as a result of the changes in the microstructure: a significant yield stress is measured, and under continuous shear the fluid is shear-thinning. The rheological properties, in particular the dynamic and static shear stress, were studied as a function of particle volume fraction for various strengths (including null) of the applied electric field. The flow curves at constant shear rate can be scaled with respect to both the particle fraction and electric field strength onto a master curve. This scaling is consistent with simple scaling arguments. The shape of the master curve accounts for the system's complexity; it approaches a standard power-law model at high Mason numbers. Both dynamic and static yield stresses are observed to depend on the particle fraction Phi and electric field E as PhibetaEalpha, with alpha approximately 1.85 and beta approximately 1 and 1.70 for the dynamic and static yield stresses, respectively. The yield stress was also determined as the critical stress at which there occurs a bifurcation in the rheological behavior of suspensions that are submitted to a constant shear stress; a scaling law with alpha approximately 1.84 and beta approximately 1.70 was obtained. The effectiveness of the latter technique confirms that such electrorheological (ER) fluids can be studied in the framework of thixotropic fluids. The method

  5. A consistent method for finite volume discretization of body forces on collocated grids applied to flow through an actuator disk

    DEFF Research Database (Denmark)

    Troldborg, Niels; Sørensen, Niels N.; Réthoré, Pierre-Elouan

    2015-01-01

    This paper describes a consistent algorithm for eliminating the numerical wiggles appearing when solving the finite volume discretized Navier-Stokes equations with discrete body forces in a collocated grid arrangement. The proposed method is a modification of the Rhie-Chow algorithm where the for...

  6. Compressible Fluid Suspension Performance Testing

    National Research Council Canada - National Science Library

    Hoogterp, Francis

    2003-01-01

    ... compressible fluid suspension system that was designed and installed on the vehicle by DTI. The purpose of the tests was to evaluate the possible performance benefits of the compressible fluid suspension system...

  7. Multiobjective suspension control problem

    NARCIS (Netherlands)

    Jager, de A.G.

    1995-01-01

    The paper describes a (controller) design problem in the field of suspension systems for transport vehicles. A ten degrees-of-freedom model for a tractor-semitrailer vehicle is presented, using parameters derived from a real vehicle, which should be used for design and verification purposes. Road

  8. Bidisperse and polydisperse suspension rheology at large solid fraction

    Energy Technology Data Exchange (ETDEWEB)

    Pednekar, Sidhant [Benjamin Levich Institute and Department of Chemical Engineering, The City College of New York, New York, New York 10031; Chun, Jaehun [Pacific Northwest National Laboratory, Richland, Washington 99352; Morris, Jeffrey F. [Benjamin Levich Institute and Department of Chemical Engineering, The City College of New York, New York, New York 10031

    2018-03-01

    At the same solid volume fraction, bidisperse and polydisperse suspensions display lower viscosities, and weaker normal stress response, compared to monodisperse suspensions. The reduction of viscosity associated with size distribution can be explained by an increase of the maximum flowable, or jamming, solid fraction. In this work, concentrated or "dense" suspensions are simulated under strong shearing, where thermal motion and repulsive forces are negligible, but we allow for particle contact with a mild frictional interaction with interparticle friction coefficient of 0.2. Aspects of bidisperse suspension rheology are first revisited to establish that the approach reproduces established trends; the study of bidisperse suspensions at size ratios of large to small particle radii (2 to 4) shows that a minimum in the viscosity occurs for zeta slightly above 0.5, where zeta=phi_{large}/phi is the fraction of the total solid volume occupied by the large particles. The simple shear flows of polydisperse suspensions with truncated normal and log normal size distributions, and bidisperse suspensions which are statistically equivalent with these polydisperse cases up to third moment of the size distribution, are simulated and the rheologies are extracted. Prior work shows that such distributions with equivalent low-order moments have similar phi_{m}, and the rheological behaviors of normal, log normal and bidisperse cases are shown to be in close agreement for a wide range of standard deviation in particle size, with standard correlations which are functionally dependent on phi/phi_{m} providing excellent agreement with the rheology found in simulation. The close agreement of both viscosity and normal stress response between bi- and polydisperse suspensions demonstrates the controlling in influence of the maximum packing fraction in noncolloidal suspensions. Microstructural investigations and the stress distribution according to particle size are also presented.

  9. Equivalent Air Spring Suspension Model for Quarter-Passive Model of Passenger Vehicles.

    Science.gov (United States)

    Abid, Haider J; Chen, Jie; Nassar, Ameen A

    2015-01-01

    This paper investigates the GENSIS air spring suspension system equivalence to a passive suspension system. The SIMULINK simulation together with the OptiY optimization is used to obtain the air spring suspension model equivalent to passive suspension system, where the car body response difference from both systems with the same road profile inputs is used as the objective function for optimization (OptiY program). The parameters of air spring system such as initial pressure, volume of bag, length of surge pipe, diameter of surge pipe, and volume of reservoir are obtained from optimization. The simulation results show that the air spring suspension equivalent system can produce responses very close to the passive suspension system.

  10. Peripheral arterial volume distensibility: significant differences with age and blood pressure measured using an applied external pressure

    International Nuclear Information System (INIS)

    Zheng, Dingchang; Murray, Alan

    2011-01-01

    A new arterial distensibility measurement technique was assessed in 100 healthy normotensive subjects. Arterial transmural pressures on the whole right arm were reduced with a 50 cm long cuff inflated to 10, 20, 30 and 40 mmHg. The electrocardiogram, and finger and ear photoplethysmograms were recorded simultaneously. Arm pulse propagation time, pulse wave velocity (PWV) and arterial volume distensibility were determined. With a 40 mmHg reduction in transmural pressure, arm pulse propagation time increased from 61 to 83 ms, PWV decreased from 12 to 8 m s −1 and arterial distensibility increased from 0.102% to 0.232% per mmHg (all P < 0.0001). At all cuff pressures, arterial distensibility was significantly related to resting mean arterial pressure (MAP), diastolic blood pressure (DBP) and age, and for systolic blood pressure at 30 and 40 mmHg (all P < 0.05). At 40 mmHg cuff pressure, arterial distensibility fell by 54% for a MAP increase from 75 to 105 mmHg, 57% for a DBP increase from 60 to 90 mmHg and 47% for an age increase from 20 to 70 years. These changes were more than double than those without cuff pressure. Our technique showed that systemic volume distensibility of the peripheral arm artery reduced with age, with a greater effect at higher external and lower transmural pressures

  11. Environmental Restoration/Waste Management - applied technology. Semiannual report, July 1992--June 1993, Volume 1, Number 2, and Volume 2, Number 1

    International Nuclear Information System (INIS)

    Murphy, P.W.; Bruner, J.M.; Price, M.E.; Talaber, C.J.

    1993-01-01

    The Environmental Restoration/Waste Management-Applied Technology (ER/WM-AT) Program is developing restoration and waste treatment technologies needed for the ongoing environmental cleanup of the Department of Energy (DOE) complex and treatment technologies for wastes generated in the nuclear weapons production complex. These technologies can find application to similar problems nationally and even worldwide. They can be demonstrated at the Livermore site, which mirrors (on a small scale) many of the environmental and waste management problems of the rest of the DOE complex. Their commercialization should speed cleanup, and the scope of the task should make it attractive to US industry. The articles in this semi-annual report cover the following areas: ceramic final forms for residues of mixed waste treatment; treatment of wastes containing sodium nitrate; actinide volatility in thermal oxidation processes; in situ microbial filters for remediating contaminated soils; collaboration with scientists in the former Soviet Union on new ER/WM technologies; and fiber-optic sensors for chlorinated organic solvents

  12. Particle Image Velocimetry (PIV) Measurements of Suspension-Feeding Velocities

    Science.gov (United States)

    Du Clos, K.; Jones, I. T.; Carrier, T. J.; Jumars, P. A.

    2016-02-01

    Active suspension feeders, such as bivalves and tunicates, connect benthic and pelagic ecosystems by packaging suspended matter into larger fecal and pseudofecal particles, greatly enhancing the flux of carbon and nutrients from the water column to the benthos. The volume of water processed by a population of suspension feeders is commonly estimated by scaling up results from experiments that measure the clearance rate (the volume of water cleared of particles per time) of one or a few individual suspension feeders. Clearance rates vary, however, between species, within a species, and over time for a single individual; and the velocity fields produced by suspension feeders are likely to interact in complex ways. We measured the water velocity fields produced by two species of bivalve, Mya arenaria and Mercenaria mercenaria, and the tunicate Ciona intestinalis, using particle image velocimetry (PIV). We used these measurements to calculate flow rates and Reynolds numbers of inhalant and exhalant siphons. We also observed strong entrainment of water by M. arenaria's exhalant siphon jet that may help to explain how the clam avoids depleting the water around it of particles and oxygen as it feeds. We are using these measurements to inform computational fluid mechanics (CFD) models of suspension feeding, allowing us to examine the interactions of flow fields produced by multiple suspension feeders and other effects not quantified by clearance-rate measurements.

  13. 40 CFR 1054.635 - What special provisions apply for small-volume engine and equipment manufacturers?

    Science.gov (United States)

    2010-07-01

    ... provisions apply as specified in this part. (b) If you are a small business (as defined by the Small Business... be expected to fulfill future regulatory obligations and administrative judgments. We may also... before you certify your engines for the next model year, we might allow you to use assigned deterioration...

  14. Influence of crystal habit on trimethoprim suspension formulation.

    Science.gov (United States)

    Tiwary, A K; Panpalia, G M

    1999-02-01

    The role of crystal habit in influencing the physical stability and pharmacokinetics of trimethoprim suspensions was examined. Different habits for trimethoprim (TMP) were obtained by recrystallizing the commercial sample (PD) utilizing solvent-change precipitation method. Four distinct habits (microscopic observation) belonging to the same polymorphic state (DSC studies) were selected for studies. Preformulation and formulation studies were carried out on suspension dosage forms containing these crystals. The freshly prepared suspensions were also evaluated for their pharmacokinetic behaviour on healthy human volunteers using a cross over study. Variation of crystallization conditions produces different habits of TMP. Among the different crystal habits exhibiting same polymorphic state, the most anisometric crystal showed best physical stability in terms of sedimentation volume and redispersibility. However, habit did not significantly affect the extent of TMP excreted in urine. Modification of surface morphology without significantly altering the polymorphic state can be utilized for improving physical stability of TMP suspensions. However, the pharmacokinetic profile remains unaltered.

  15. Particle interactions in concentrated suspensions

    International Nuclear Information System (INIS)

    Mondy, L.A.; Graham, A.L.; Abbott, J.R.; Brenner, H.

    1993-01-01

    An overview is presented of research that focuses on slow flows of suspensions in which colloidal and inertial effects are negligibly small. The authors describe nuclear magnetic resonance imaging experiments to quantitatively measure particle migration occurring in concentrated suspensions undergoing a flow with a nonuniform shear rate. These experiments address the issue of how the flow field affects the microstructure of suspensions. In order to understand the local viscosity in a suspension with such a flow-induced, spatially varying concentration, one must know how the viscosity of a homogeneous suspension depends on such variables as solids concentration and particle orientation. The authors suggest the technique of falling ball viscometry, using small balls, as a method to determine the effective viscosity of a suspension without affecting the original microstructure significantly. They also describe data from experiments in which the detailed fluctuations of a falling ball's velocity indicate the noncontinuum nature of the suspension and may lead to more insights into the effects of suspension microstructure on macroscopic properties. Finally, they briefly describe other experiments that can be performed in quiescent suspensions (in contrast to the use of conventional shear rotational viscometers) in order to learn more about boundary effects in concentrated suspensions

  16. Development of an Air Pneumatic Suspension System for Transtibial Prostheses

    Directory of Open Access Journals (Sweden)

    Gholamhossein Pirouzi

    2014-09-01

    Full Text Available The suspension system and socket fitting of artificial limbs have major roles and vital effects on the comfort, mobility, and satisfaction of amputees. This paper introduces a new pneumatic suspension system that overcomes the drawbacks of current suspension systems in donning and doffing, change in volume during daily activities, and pressure distribution in the socket-stump interface. An air pneumatic suspension system (APSS for total-contact sockets was designed and developed. Pistoning and pressure distribution in the socket-stump interface were tested for the new APSS. More than 95% of the area between each prosthetic socket and liner was measured using a Tekscan F-Scan pressure measurement which has developed matrix-based pressure sensing systems. The variance in pressure around the stump was 8.76 kPa. APSS exhibits less pressure concentration around the stump, improved pressure distribution, easy donning and doffing, adjustability to remain fitted to the socket during daily activities, and more adaptability to the changes in stump volume. The volume changes were adjusted by utility of air pressure sensor. The vertical displacement point and reliability of suspension were assessed using a photographic method. The optimum pressure in every level of loading weight was 55 kPa, and the maximum displacement was 6 mm when 90 N of weight was loaded.

  17. Shear-induced particle migration in suspensions of rods

    Energy Technology Data Exchange (ETDEWEB)

    Mondy, L.A. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States)); Brenner, H. (Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)); Altobelli, S.A. (The Lovelace Institutes, 2425 Ridgecrest Drive, S. E., Albuquerque, New Mexico 87108 (United States)); Abbott, J.R.; Graham, A.L. (Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

    1994-03-01

    Shear-induced migration of particles occurs in suspensions of neutrally buoyant spheres in Newtonian fluids undergoing shear in the annular space between two rotating, coaxial cylinders (a wide-gap Couette), even when the suspension is in creeping flow. Previous studies have shown that the rate of migration of spherical particles from the high-shear-rate region near the inner (rotating) cylinder to the low-shear-rate region near the outer (stationary) cylinder increases rapidly with increasing sphere size. To determine the effect of particle shape, the migration of rods suspended in Newtonian fluids was recently measured. The behavior of several suspensions was studied. Each suspension contained well-characterized, uniform rods with aspect ratios ranging from 2 to 18 at either 0.30 or 0.40 volume fraction. At the same volume fraction of solids, the steady-state, radial concentration profiles for rods were independent of aspect ratio and were indistinguishable from those obtained from suspended spheres. Only minor differences near the walls (attributable to the finite size of the rods relative to the curvature of the walls) appeared to differentiate the profiles. Data taken during the transition from a well-mixed suspension to the final steady state show that the rate of migration increased as the volume of the individual rods increased.

  18. Rheological Modeling of Macro Viscous Flows of Granular Suspension of Regular and Irregular Particles

    Directory of Open Access Journals (Sweden)

    Anna Maria Pellegrino

    2017-12-01

    Full Text Available This paper refers to complex granular-fluid mixtures involved into geophysical flows, such as debris and hyper-concentrated flows. For such phenomena, the interstitial fluids play a role when they are in the viscous regime. Referring to experiments on granular-fluid mixture carried out with pressure imposed annular shear cell, we study the rheological behaviour of dense mixture involving both spheres and irregular-shaped particles. For the case of viscous suspensions with irregular grains, a significant scatter of data from the trend observed for mixtures with spherical particles was evident. In effect, the shape of the particles likely plays a fundamental role in the flow dynamics, and the constitutive laws proposed by the frictional theory for the spheres are no longer valid. Starting from the frictional approach successfully applied to suspension of spheres, we demonstrate that also in case of irregular particles the mixture rheology may be fully characterized by the two relationships involving friction coefficient µ and volume concentration Ф as a function of the dimensionless viscous number Iv. To this goal, we provided a new consistent general model, referring to the volume fraction law and friction law, which accounts for the particle shape. In this way, the fitting parameters reduce just to the static friction angle µ1, and the two parameters, k and fs related to the grain shape. The resulting general model may apply to steady fully developed flows of saturated granular fluid mixture in the viscous regime, no matter of granular characteristics.

  19. Glass transition and aging in dense suspensions of thermosensitive microgel particles

    NARCIS (Netherlands)

    Purnomo, E.H; van den Ende, Henricus T.M.; Vanapalli Veera, V.S.A.R.; Vanapalli, Srinivas; Mugele, Friedrich Gunther

    2008-01-01

    We report a thermosensitive microgel suspension that can be tuned reversibly between the glass state at low temperature and the liquid state at high temperature. Unlike hard spheres, we find that the glass transition for these suspensions is governed by both the volume fraction and the softness of

  20. Study on Dynamic Behaviour of Wishbone Suspension System

    International Nuclear Information System (INIS)

    Kamal, M; Rahman, M M

    2012-01-01

    This paper presents the characteristic model of the wishbone suspension system using the quarter car model approach. Suspension system in an automobile provides vehicle control and passenger comfort by providing isolation from road disturbances. This makes it essential that the detailed behavior of suspension should be known to optimize the performance. A kinetic study is performed using multi body system (MBS) analysis. The dirt road profile is considered as an applied loading. The spring constant, damping coefficient and sprung mass are studied on the performance of the suspension system. It can be observed that the spring constant is inversely related with time required to return to initial position and the amount of deformations. The damping ratio affects the suppression of spring oscillations, beyond a certain limit damping ration has the negligible effect. Sprung mass effected the equilibrium position of the suspension system with a small effect on its oscillation behavior. It is shown that the spring constant, damping ratio and sprung mass are significant parameters to design the suspension system. This study is essential for complete understanding of working of the suspension system and a future study with real geometries.

  1. Assessment of railway wagon suspension characteristics

    Science.gov (United States)

    Soukup, Josef; Skočilas, Jan; Skočilasová, Blanka

    2017-05-01

    The article deals with assessment of railway wagon suspension characteristics. The essential characteristics of a suspension are represented by the stiffness constants of the equivalent springs and the eigen frequencies of the oscillating movements in reference to the main central inertia axes of a vehicle. The premise of the experimental determination of these characteristic is the knowledge of the gravity center position and the knowledge of the main central inertia moments of the vehicle frame. The vehicle frame performs the general spatial movement when the vehicle moves. An analysis of the frame movement generally arises from Euler's equations which are commonly used for the description of the spherical movement. This solution is difficult and it can be simplified by applying the specific assumptions. The eigen frequencies solutions and solutions of the suspension stiffness are presented in the article. The solutions are applied on the railway and road vehicles with the simplifying conditions. A new method which assessed the characteristics is described in the article.

  2. Suspensions of colloidal particles and aggregates

    CERN Document Server

    Babick, Frank

    2016-01-01

    This book addresses the properties of particles in colloidal suspensions. It has a focus on particle aggregates and the dependency of their physical behaviour on morphological parameters. For this purpose, relevant theories and methodological tools are reviewed and applied to selected examples. The book is divided into four main chapters. The first of them introduces important measurement techniques for the determination of particle size and interfacial properties in colloidal suspensions. A further chapter is devoted to the physico-chemical properties of colloidal particles—highlighting the interfacial phenomena and the corresponding interactions between particles. The book’s central chapter examines the structure-property relations of colloidal aggregates. This comprises concepts to quantify size and structure of aggregates, models and numerical tools for calculating the (light) scattering and hydrodynamic properties of aggregates, and a discussion on van-der-Waals and double layer interactions between ...

  3. Large Scale Brownian Dynamics of Confined Suspensions of Rigid Particles

    Science.gov (United States)

    Donev, Aleksandar; Sprinkle, Brennan; Balboa, Florencio; Patankar, Neelesh

    2017-11-01

    We introduce new numerical methods for simulating the dynamics of passive and active Brownian colloidal suspensions of particles of arbitrary shape sedimented near a bottom wall. The methods also apply for periodic (bulk) suspensions. Our methods scale linearly in the number of particles, and enable previously unprecedented simulations of tens to hundreds of thousands of particles. We demonstrate the accuracy and efficiency of our methods on a suspension of boomerang-shaped colloids. We also model recent experiments on active dynamics of uniform suspensions of spherical microrollers. This work was supported in part by the National Science Foundation under award DMS-1418706, and by the U.S. Department of Energy under award DE-SC0008271.

  4. Stability of allopurinol and of five antineoplastics in suspension.

    Science.gov (United States)

    Dressman, J B; Poust, R I

    1983-04-01

    The stability of allopurinol, azathioprine, chlorambucil, melphalan, mercaptopurine, and thioguanine each in an extemporaneously prepared suspension was studied. Tablets of each drug were crushed, mixed with a suspending agent, and brought to a final volume of 10, 15, or 20 ml with a 2:1 mixture of simple syrup and wild cherry syrup. Suspensions were prepared in the following concentrations: allopurinol (20 mg/ml), azathioprine (50 mg/ml), chlorambucil (2 mg/ml), melphalan (2 mg/ml), mercaptopurine (50 mg/ml), and thioguanine (40 mg/ml). Using high-performance liquid chromatography or ultraviolet scans, duplicate assays were performed on each suspension periodically during storage for up to 84 days at ambient room temperature or 5 degrees C. The time required for the suspensions to drop below 90% of labeled strength was used as an indicator of drug stability. Allopurinol and azathioprine were stable for at least 56 days at room temperature and at 5 degrees C. Chlorambucil decomposed rapidly at room temperature but was stable for seven days when stored at 5 degrees C. Melphalan suspensions did not meet the stated criteria for stability even at the time of initial assay. Mercaptopurine and thioguanine were stable for 14 and 84 days, respectively, at room temperature; at 5 degrees C, assay values dropped below those obtained at room temperature. In the suspension formulation tested, allopurinol, azathioprine, mercaptopurine, and thioguanine are stable for at least 14 days at room temperature; chlorambucil suspensions should be refrigerated and discarded after seven days. Melphalan decomposes too rapidly to make this suspension formulation feasible for extemporaneous compounding.

  5. Magnetorheological suspension electromagnetic brake

    International Nuclear Information System (INIS)

    Bica, Ioan

    2004-01-01

    The magnetorheological suspension (MRS) brake is of the monoblock type. The main part of the electromagnetic brake is an electromagnet, between whose poles two MRS disks are placed. For distances between disks of 0.65x10 -3 m±10%, revolutions of the electric motor, coupled to the electromagnetic brake, ranging between 200 and 1600 rev/min and braking powers of up to 85 W, there are no differences in revolutions between the disks of the electromagnetic brake. For fixed revolutions of the electric motor, the revolution of the parallel disk can be modified continuously by means of the intensity of the magnetic field. In all cases, the quantity of MRS is of 0.35x10 -3 kg

  6. A magnetic suspension system for measuring liquid density

    Directory of Open Access Journals (Sweden)

    Luz María Centeno González

    2013-01-01

    Full Text Available Density is a derived quantity of mass and length; it is defined as mass per volume unit and its SI unit is kg/m3. National metrology institutes have been designing and building their own magnetic suspension systems during the last 5 decades for making fluid density measurements; this has allowed them to carry out research into liquids and gases’ physical characteristics. This paper was aimed at designing and developing a magnetic suspension system for a magnetic balance used in determining liquid density to be used in CENAM’s metrology density laboratories.

  7. Mesoscopic Length Scale Controls the Rheology of Dense Suspensions

    Science.gov (United States)

    Bonnoit, Claire; Lanuza, Jose; Lindner, Anke; Clement, Eric

    2010-09-01

    From the flow properties of dense granular suspensions on an inclined plane, we identify a mesoscopic length scale strongly increasing with volume fraction. When the flowing layer height is larger than this length scale, a diverging Newtonian viscosity is determined. However, when the flowing layer height drops below this scale, we evidence a nonlocal effective viscosity, decreasing as a power law of the flow height. We establish a scaling relation between this mesoscopic length scale and the suspension viscosity. These results support recent theoretical and numerical results implying collective and clustered granular motion when the jamming point is approached from below.

  8. Hydrodynamic dispersion of microswimmers in suspension

    Science.gov (United States)

    Martin, Matthieu; Rafaï, Salima; Peyla, Philippe

    2014-11-01

    In our laboratory, we study hydrodynamics of suspensions of micro-swimmers. These micro-organisms are unicellular algae Chlamydomonas Rheinhardii which are able to swim by using their flagella. The swimming dynamics of these micro-swimmers can be seen as a random walk, in absence of any kind of interaction. In addition, these algae have the property of being phototactic, i.e. they swim towards the light. Combining this property with a hydrodynamic flow, we were able to reversibly separate algae from the rest of the fluid. But for sufficiently high volume fraction, these active particles interact with each other. We are now interested in how the coupling of hydrodynamic interactions between swimmers and phototaxis can modify the swimming dynamics at the scale of the suspension. To this aim, we conduct experiments in microfluidic devices to study the dispersion of the micro-organisms in a the liquid phase as a function of the volume fraction. We show that the dispersion of an assembly of puller type microswimmers is quantitatively affected by hydrodynamics interactions. Phd student.

  9. Sedimentation in Particulate Aqueous Suspensions as studied by means of Dielectric Time Domain Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Pettersen, Bjoernar Hauknes

    1997-12-31

    Many problems in offshore oil production and multiphase transport are related to surface and colloid chemistry. This thesis applies dielectric spectroscopy as an experimental technique to study the behaviour of particle suspensions in polar media. The thesis opens with an introduction to suspensions and time domain dielectric spectroscopy. It then investigates the dielectric properties of silica and alumina dispersed in polar solvents. It is found that theoretical models can be used to calculate the volume fraction disperse phase in the suspension and that the particle sedimentation depends on the wetting of the particles, charge on the particle surface and viscosity of the solvent, and that this dependency can be measured by time domain dielectric spectroscopy. When the surface properties of silica and alumina particles were modified by coating them with a non-ionic polymer and a non-ionic surfactant, then different degrees of packing in the sedimented phase at the bottom of the sedimentation vessel occurred. Chemometrical methods on the synthesis of monodisperse silica particles were used to investigate what factors influence the particle size. It turned out that it is insufficient to consider only main variables when discussing the results of the synthesis. By introducing interaction terms, the author could explain the variation in the size of particles synthesized. The difference in the sedimentation rate of monodisperse silica particles upon variation of volume fraction particles, pH, salinity, amount of silanol groups at the particle surface and temperature was studied. The cross interactions play an important role and a model explaining the variation in sedimentation is introduced. Finally, magnetic particles dispersed in water and in an external magnetic field were used to study the impact on the sedimentation due to the induced flocculation. 209 refs., 90 figs., 9 tabs.

  10. Characterization of Complex Colloidal Suspensions

    Science.gov (United States)

    Seaman, J. C.; Guerin, M.; Jackson, B. P.; Ranville, J. M.

    2003-04-01

    Surface chemical reactions play a major role in controlling contaminant fate and transport in the subsurface environment. Recent field and laboratory evidence suggests that mobile soil and groundwater colloids may facilitate the migration of sparingly soluble groundwater contaminants. Colloidal suspensions collected in the field or generated in laboratory column experiments tend to be fairly dilute in nature and comprised of relatively small particulates (reserved for studying ideal systems to the characterization of mobile colloids. However, many of these analytical techniques, including total/selective dissolution methods, dynamic light scattering, micro-electrophoresis, streaming potential, and even scanning electron microscopy (SEM), can be biased in of larger size fractions, and therefore, extremely sensitive to sampling, storage, and fractionation artifacts. In addition, surface modifiers such as sorbed oxides or organics can alter particulate appearance, composition, and behavior when compared to synthetic analogues or mineral standards. The current presentation will discuss the limitations and inherent biases associated with a number of analytical characterization techniques that are commonly applied to the study of mobile soil and groundwater colloids, including field flow fractionation (FFF) and acoustic based methods that have only recently become available.

  11. Physical gelation of a microfiber suspension.

    Science.gov (United States)

    Perazzo, Antonio; Nunes, Janine K.; Guido, Stefano; Stone, Howard A.

    2015-11-01

    Hydrogels are among the most exploited materials in tissue engineering and there is growing interest in injectable hydrogels, especially as applied to surgical adhesives and bioprinting materials. Here we report a method to produce a hydrogel in a desired location by simply extruding a suspension of high aspect ratio and flexible microfibers from a syringe. The mechanism of gel formation is purely physical and based on irreversible entanglements formed by the microfibers under the action of flow. The single microfibers have been produced and finely tailored by microfluidic methods. Shear rheology has been performed in order to get insights on the entanglements, and results show that the formation of entanglements is related to a shear thickening behavior of the suspension, which in turn depends on shear rate and concentration of fibers. When shearing the suspension, highly non-linear viscoelastic behavior is observed and probed by a highly positive first normal stress difference. We also report the hydrogel swelling behavior and its linear viscoelastic properties as obtained by imposing small oscillatory stress to the material.

  12. Armoring confined bubbles in concentrated colloidal suspensions

    Science.gov (United States)

    Yu, Yingxian; Khodaparast, Sepideh; Stone, Howard

    2016-11-01

    Encapsulation of a bubble with microparticles is known to significantly improve the stability of the bubble. This phenomenon has recently gained increasing attention due to its application in a variety of technologies such as foam stabilization, drug encapsulation and colloidosomes. Nevertheless, the production of such colloidal armored bubble with controlled size and particle coverage ratio is still a great challenge industrially. We study the coating process of a long air bubble by microparticles in a circular tube filled with a concentrated microparticles colloidal suspension. As the bubble proceeds in the suspension of particles, a monolayer of micro-particles forms on the interface of the bubble, which eventually results in a fully armored bubble. We investigate the phenomenon that triggers and controls the evolution of the particle accumulation on the bubble interface. Moreover, we examine the effects of the mean flow velocity, the size of the colloids and concentration of the suspension on the dynamics of the armored bubble. The results of this study can potentially be applied to production of particle-encapsulated bubbles, surface-cleaning techniques, and gas-assisted injection molding.

  13. Boundary Effects and Shear Thickening of Colloidal Suspensions: A study based on measurement of Suspension Microstructure

    Science.gov (United States)

    Perera, M. Tharanga D.

    coverslips, and over rough walls having a high density coating of particles. These results show that there is more order in structure near smooth boundaries while near rough boundaries the structure is similar to that found in the bulk. The relative viscosity and normal stress differences also indicate that boundaries have an effect up as far as 6 particle diameters away from the boundary. Finally, we investigate the microstructure evolvement in a model porous medium and notice that such boundary effects come into play in such real process flows. The confocal microscopy technique also provides us with the advantage of measuring structure in real process flows. We have investigated how the microstructure evolves upstream and downstream in a porous medium. We notice more structure in a high volume fraction suspension and notice anisotropic behavior at regions where shear from the wall of the posts dominate. In other cases, a mixed flow behavior is observed due to collisions between pore surfaces and other particles resulting in a deviation from flow streamlines.

  14. Controlling active cabin suspensions in commercial vehicles

    NARCIS (Netherlands)

    Evers, W.J.E.; Besselink, I.J.M.; Teerhuis, A.P.; Knaap, van der A.C.M.; Nijmeijer, H.

    2009-01-01

    The field of automotive suspensions is changing. Semi-active and active suspensions are starting to become viable options for vehicle designers. Suspension design for commercial vehicles is especially interesting given its potential. An active cabin suspension for a heavy-duty truck is considered,

  15. Neonatal mannequin comparison of the Upright self-inflating bag and snap-fit mask versus standard resuscitators and masks: leak, applied load and tidal volumes.

    Science.gov (United States)

    Rafferty, Anthony Richard; Johnson, Lucy; Davis, Peter G; Dawson, Jennifer Anne; Thio, Marta; Owen, Louise S

    2017-11-30

    Neonatal mask ventilation is a difficult skill to acquire and maintain. Mask leak is common and can lead to ineffective ventilation. The aim of this study was to determine whether newly available neonatal self-inflating bags and masks could reduce mask leak without additional load being applied to the face. Forty operators delivered 1 min episodes of mask ventilation to a mannequin using the Laerdal Upright Resuscitator, a standard Laerdal infant resuscitator (Laerdal Medical) and a T-Piece Resuscitator (Neopuff), using both the Laerdal snap-fit face mask and the standard Laerdal size 0/1 face mask (equivalent sizes). Participants were asked to use pressure sufficient to achieve 'appropriate' chest rise. Leak, applied load, airway pressure and tidal volume were measured continuously. Participants were unaware that load was being recorded. There was no difference in mask leak between resuscitation devices. Leak was significantly lower when the snap-fit mask was used with all resuscitation devices, compared with the standard mask (14% vs 37% leak, Pmask was preferred by 83% of participants. The device-mask combinations had no significant effect on applied load. The Laerdal Upright Resuscitator resulted in similar leak to the other resuscitation devices studied, and did not exert additional load to the face and head. The snap-fit mask significantly reduced overall leak with all resuscitation devices and was the mask preferred by participants. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  16. "Point de suspension"

    CERN Multimedia

    2004-01-01

    CERN - Globe of Science and Innovation 20 and 21 October Acrobatics, mime, a cappella singing, projections of images, a magical setting... a host of different tools of a grandeur matching that of the Universe they relate. A camera makes a massive zoom out to reveal the multiple dimensions of Nature. Freeze the frame: half way between the infinitesimally small and the infinitesimally large, a man suspends his everyday life (hence the title "Point de Suspension", which refers to the three dots at the end of an uncompleted sentence) to take a glimpse of the place he occupies in the great history of the Universe. An unusual perspective on what it means to be a human being... This wondrous show in the Globe of Science and Innovation, specially created by the Miméscope* company for the official ceremony marking CERN's fiftieth anniversary, is a gift from the Government of the Republic and Canton of Geneva, which also wishes to share this moment of wonder with the local population. There will be three perfo...

  17. "Point de suspension"

    CERN Multimedia

    2004-01-01

    http://www.cern.ch/cern50/ CERN - Globe of Science and Innovation 20 and 21 October Acrobatics, mime, a cappella singing, projections of images, a magical setting... a host of different tools of a grandeur matching that of the Universe they relate. A camera makes a massive zoom out to reveal the multiple dimensions of Nature. Freeze the frame: half way between the infinitesimally small and the infinitesimally large, a man suspends his everyday life (hence the title "Point de Suspension", which refers to the three dots at the end of an uncompleted sentence) to take a glimpse of the place he occupies in the great history of the Universe. An unusual perspective on what it means to be a human being... This wondrous show in the Globe of Science and Innovation, specially created by the Miméscope* company for the official ceremony marking CERN's fiftieth anniversary, is a gift from the Government of the Republic and Canton of Geneva, which also wishes to share this moment of wonder with the local pop...

  18. "Point de suspension"

    CERN Multimedia

    2004-01-01

    CERN - Globe of Science and Innovation 20 and 21 October Acrobatics, mime, a cappella singing, projections of images, a magical setting... a host of different tools of a grandeur matching that of the Universe they relate. A camera makes a massive zoom out to reveal the multiple dimensions of Nature. Freeze the frame: half way between the infinitesimally small and the infinitesimally large, a man suspends his everyday life (hence the title "Point de Suspension", which refers to the three dots at the end of an uncompleted sentence) to take a glimpse of the place he occupies in the great history of the Universe. An unusual perspective on what it means to be a human being... This spectacle in the Globe of Science and Innovation, specially created by the Miméscope* company for the official ceremony marking CERN's fiftieth anniversary, is a gift from the Government of the Republic and Canton of Geneva, which also wishes to share this moment of wonder with the local population. There will be three performances for...

  19. Shear-induced changes of electrical conductivity in suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Crawshaw, John; Meeten, Gerald [Schlumberger Cambridge Research, Cambridge (United Kingdom)

    2006-12-15

    The effect of shear on electrical conductivity (rheo-conduction) is studied to give information about particle behaviour in suspensions. Past work is reviewed, and expressions are derived for the rheo-conduction of a suspension of nonconducting spheroids in a conducting matrix for current flow, parallel and normal to the suspension flow direction. A simple apparatus to study rheo-conduction in pipe flow is described, and measurements of steady and time-dependent effects are reported for various suspensions of colloidal particles. Suspensions of anisometric rod- and platelike particles at low concentrations showed rheo-conductive changes of sign, magnitude and relaxation that were consistent with the particle shape, concentration and interactions. The rheo-conductive response decreased with increasing volume fraction for platelike kaolinite particles, attributed to orientational jamming. Spherical latex particles gave unexpected rheo-conductive changes consistent with shear disruption of a conductive network of particles. It is concluded that rheo-conduction measurements are a useful adjunct to conventional rheometry. (orig.)

  20. Multiphase modeling of settling and suspension in anaerobic digester

    International Nuclear Information System (INIS)

    Yu, Liang; Ma, Jingwei; Frear, Craig; Zhao, Quanbao; Dillon, Robert; Li, Xiujin; Chen, Shulin

    2013-01-01

    Highlights: • Develop biowaste fluid dynamics for collision, aggregation and breakup of clusters. • Explore the mechanisms of settling and suspension in anaerobic digester. • Biowaste particles tended to have fluid properties. • Aided with CFD simulation, the scale-up effect was reduced. - Abstract: Effective suspension and settling are critical for controlling biomass retention in a bioreactor. In this paper, a multi-fluid model with kinetic theory of granular flow (KTGF) was established to describe these phenomena in the biowaste particles flow in anaerobic digesters. Solid retention time (SRT) was added as a parameter into anaerobic digestion No.1 (ADM1) model to evaluate its effect on the biogas productivity. The model was experimentally validated in a liquid–gas–solid column reactor with gas and solid volume fraction and granular temperature as the major variables. The wastewater residence time distribution was also determined through modeling and measurement to evaluate the mixing pattern in the pilot column reactor. The effect of restitution coefficient on flow behavior of biowaste particles, particles settling and suspension were predicted. Settling and suspension processes of anaerobic digesters were simulated for lab and pilot-scale reactors with comparisons made for reactor configuration and geometry model, respectively. This study demonstrated that the multi-fluid model with KTGF could provide better understanding of impact of suspension and settling upon retaining biomass particles in the anaerobic digesters

  1. Stability of an extemporaneously prepared thalidomide suspension.

    Science.gov (United States)

    Kraft, Shawna; Johnson, Cary E; Tyler, Ryan P

    2012-01-01

    The short-term physical and chemical stability of an oral suspension of thalidomide 20 mg/mL was studied. An oral suspension of thalidomide 20 mg/mL was prepared by emptying the contents of 12 100-mg thalidomide capsules into a glass mortar; 30 mL of Ora-Plus and 30 mL of Ora-Sweet were mixed and added to the thalidomide powder to make a final volume of 60 mL. Three identical samples of the formulation were prepared and placed in 2-oz amber plastic bottles with child-resistant caps and stored under refrigeration (3-5 °C). A 1-mL sample was withdrawn from each of the three samples with a micropipette immediately after preparation and at 7, 14, 21, 28, and 35 days. After further dilution to an expected concentration of 20 μg/mL with acetonitrile-methanol and then dilution with mobile phase, the samples were assayed in duplicate using stability-indicating high-performance liquid chromatography. Stability was determined by evaluating the percentage of the initial concentration remaining at each time point; stability was defined as the retention of at least 90% of the initial concentration of thalidomide. At least 92% of the initial thalidomide concentration remained throughout the 35-day study period. There were no detectable changes in color, odor, or pH and no visible microbial growth in any sample. An extemporaneously prepared suspension of thalidomide 20 mg/mL in a 1:1 mixture of Ora-Plus and Ora-Sweet was stable for at least 35 days when stored in 2-oz amber plastic bottles under refrigeration.

  2. Stability of an extemporaneously prepared tadalafil suspension.

    Science.gov (United States)

    Pettit, Rebecca S; Johnson, Cary E; Caruthers, Regine L

    2012-04-01

    The stability of an extemporaneously prepared tadalafil oral suspension was studied. An oral suspension of tadalafil 5 mg/mL was prepared by thoroughly grinding 15 20-mg tadalafil tablets in a glass mortar. Thirty milliliters of Ora-Plus and 30 mL of Ora-Sweet were mixed and added to the powder to make a final volume of 60 mL. Three identical samples of the formulation were prepared and placed in 2-oz amber plastic bottles with child-resistant caps and stored at room temperature (23-25 °C). A 1-mL sample was withdrawn from each of the three bottles with a micropipette immediately after preparation and at 7, 14, 28, 57, and 91 days. After double dilution (1:10 and 0.1:5 v/v) to an expected concentration of 10 μg/mL with methanol and mobile phase, respectively, the samples were assayed in duplicate using stability-indicating high-performance liquid chromatography. The samples were visually examined for any color change and evaluated for pH changes on each day of analysis. Taste evaluation was performed at the beginning and end of the study. Stability was defined as the retention of at least 90% of the initial concentration. At least 99% of the initial tadalafil concentration remained throughout the 91-day study period. There were no detectable changes in color, odor, taste, and pH, and no visible microbial growth was observed in any sample. An extemporaneously prepared suspension of tadalafil 5 mg/mL in a 1:1 mixture of Ora-Plus and Ora-Sweet was stable for at least 91 days when stored in amber plastic bottles at room temperature.

  3. Stability of extemporaneously prepared moxifloxacin oral suspensions.

    Science.gov (United States)

    Hutchinson, David J; Johnson, Cary E; Klein, Kristin C

    2009-04-01

    The stability of extemporaneously prepared moxifloxacin oral suspensions was studied. An oral suspension of moxifloxacin 20 mg/mL was prepared by thoroughly grinding three 400-mg tablets of moxifloxacin in a glass mortar. Thirty milliliters of Ora-Plus and 30 mL of either Ora-Sweet or Ora-Sweet SF were mixed and added to the powder to make a final volume of 60 mL. Three identical samples of each formulation were prepared and placed in 2-oz amber plastic bottles with child-resistant caps and were stored at room temperature (23-25 degrees C). A 1-mL sample was withdrawn from each of the six bottles with a micropipette immediately after preparation and at 7, 14, 28, 60, and 90 days. After further dilution to an expected concentration of 8 microg/ mL with sample diluent, the samples were assayed in duplicate by stability-indicating high-performance liquid chromatography. Stability was defined as the retention of at least 90% of the initial concentration. At least 99% of the initial moxifloxacin remained throughout the 90-day study period in both preparations. There were no detectable changes in color, odor, taste, and pH and no visible microbial growth in any sample. Extemporaneously compounded suspensions of moxifloxacin 20 mg/mL in a 1:1 mixture of Ora-Plus and Ora-Sweet or Ora-Sweet SF were stable for at least 90 days when stored in 2-oz amber plastic bottles at room temperature.

  4. Stability of extemporaneously prepared glycopyrrolate oral suspensions.

    Science.gov (United States)

    Cober, Mary Petrea; Johnson, Cary E; Sudekum, David; Penprase, Kimberly

    2011-05-01

    The stability of extemporaneously prepared glycopyrrolate 0.5-mg/mL suspensions was evaluated. An oral suspension of glycopyrrolate 0.5 mg/mL was prepared by thoroughly grinding 30 1-mg tablets of glycopyrrolate in a glass mortar. Thirty milliliters of Ora-Plus and 30 mL of either Ora-Sweet or Ora-Sweet SF were mixed and added to the powder to make a final volume of 60 mL. Three identical samples of the formulation were prepared and placed in 2-oz amber plastic bottles with child-resistant caps and stored at room temperature (23-25 °C). A 1-mL sample was withdrawn from each of the three bottles with a micropipette immediately after preparation and 7, 15, 30, 60, and 90 days afterward. After further dilution to an expected concentration of 50 μg/mL with sample diluent, the samples were assayed in duplicate by stability-indicating high-performance liquid chromatography. The samples were visually examined for any color change and evaluated for pH on each day of analysis. Taste evaluations were performed at the beginning and end of the study. Stability was defined as the retention of at least 90% of the initial concentration. At least 95% of the initial glycopyrrolate remained throughout the 90-day study period in both preparations. There were no detectable changes in color, odor, taste, and pH, and no visible microbial growth was observed in any sample. Extemporaneously compounded suspensions of glycopyrrolate 0.5 mg/mL in a 1:1 mixture of Ora-Plus/Ora-Sweet or Ora-Plus/Ora-Sweet SF were stable for at least 90 days when stored in amber plastic bottles at room temperature.

  5. Stability of extemporaneously prepared rifaximin oral suspensions.

    Science.gov (United States)

    Cober, Mary Petrea; Johnson, Cary E; Lee, Jordan; Currie, Kenne

    2010-02-15

    The stability of extemporaneously prepared rifaximin oral suspensions was studied. An oral suspension of rifaximin 20 mg/mL was prepared by thoroughly grinding six 200-mg tablets of rifaximin in a glass mortar. Thirty milliliters of Ora-Plus and 30 mL of either Ora-Sweet or Ora-Sweet SF were mixed and added to the powder to make a final volume of 60 mL. Three identical samples of each formulation were prepared and placed in 2-oz amber plastic bottles with child-resistant caps and were stored at room temperature (23-25 degrees C). A 1-mL sample was withdrawn from each of the six bottles with a micropipette immediately after preparation and at 7, 15, 30, and 60 days. After further dilution to an expected concentration of 20 microg/mL with mobile phase, the samples were assayed in duplicate using stability-indicating high-performance liquid chromatography. The samples were visually examined for any color change and pH was tested on each day of analysis. Stability was determined by evaluating the percentage of the initial concentration remaining at each time point and defined as retention of at least 90% of the initial concentration of rifaximin. At least 99% of the initial rifaximin remained throughout the 60-day study period in both preparations. There were no detectable changes in color, odor, taste, or pH and no visible microbial growth in any sample. Extemporaneously prepared suspensions of rifaximin 20 mg/mL in 1:1 mixtures of Ora-Plus with either Ora-Sweet or Ora-Sweet SF were stable for at least 60 days when stored in 2-oz amber plastic bottles at room temperature.

  6. Startup of electrophoresis in a suspension of colloidal spheres.

    Science.gov (United States)

    Chiang, Chia C; Keh, Huan J

    2015-12-01

    The transient electrophoretic response of a homogeneous suspension of spherical particles to the step application of an electric field is analyzed. The electric double layer encompassing each particle is assumed to be thin but finite, and the effect of dynamic electroosmosis within it is incorporated. The momentum equation for the fluid outside the double layers is solved through the use of a unit cell model. Closed-form formulas for the time-evolving electrophoretic and settling velocities of the particles in the Laplace transform are obtained in terms of the electrokinetic radius, relative mass density, and volume fraction of the particles. The time scale for the development of electrophoresis and sedimentation is significantly smaller for a suspension with a higher particle volume fraction or a smaller particle-to-fluid density ratio, and the electrophoretic mobility at any instant increases with an increase in the electrokinetic particle radius. The transient electrophoretic mobility is a decreasing function of the particle volume fraction if the particle-to-fluid density ratio is relatively small, but it may increase with an increase in the particle volume fraction if this density ratio is relatively large. The particle interaction effect in a suspension on the transient electrophoresis is much weaker than that on the transient sedimentation of the particles. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Rheology of zirconia suspensions in a nonpolar organic medium

    International Nuclear Information System (INIS)

    Moloney, V.M.B.; Parris, D.; Edirisinghe, M.J.

    1995-01-01

    Three dispersants (stearic acid, oleic acid, and poly-(12-hydroxystearic acid)) are compared for their ability to produce low-viscosity suspensions of zirconia in kerosene. Rheological measurements and sediment packing density measurements show that poly(12-hydroxystearic acid) is a better dispersant than stearic acid or oleic acid; this is explained in terms of the longer tail of the poly-(12-hydroxystearic acid) surfactant molecule. The amount of dispersant can be optimized to reduce viscosity and yield point of the suspension, and to eliminate thixotropic hysteresis. The use of a dispersion medium of lower viscosity than the dispersant makes it easy to detect when complete monolayer coverage has been achieved. The loss of pseudoplasticity, brought about by a higher degree of deflocculation, can be recovered by increasing the volume fraction of solids of a suspension and this is beneficial in the plastic forming of ceramics. Rheological measurements showed that these suspensions reach a critical state above a critical shear stress (τ c ). This critical state is described by several parameters, i.e., the Bingham yield stress (τ B ), the plastic viscosity (η PL ), and the critical shear rate (γ c ), which are dependent on the volume fraction of solids

  8. Observation of antioxidant activity of leaves, callus and suspension ...

    African Journals Online (AJOL)

    GREGORY

    2011-12-16

    Dec 16, 2011 ... Antioxidant activity and phenolic compound was found in Justicia gendarussa via total phenolic content (TPC) and α,α-diphenyl-β-pycrilhydrazil hydrate (DPPH) radical scavenging assays. The assays were applied on aqueous and methanolic extracts of leaves, callus culture and cell suspension culture.

  9. Stability of extemporaneously prepared rufinamide oral suspensions.

    Science.gov (United States)

    Hutchinson, David J; Liou, Yayin; Best, Robert; Zhao, Fang

    2010-03-01

    Rufinamide is an oral antiepileptic drug indicated for adjunctive therapy in treating generalized seizures associated with Lennox-Gastaut syndrome. Currently, rufinamide is available as 200-mg and 400-mg tablets. A liquid dosage form does not exist at the present time. Lack of a suspension formulation may present an administration problem for many children and adults who are unable to swallow tablets. The availability of a liquid dosage form will provide an easy and accurate way to measure and administer the medication. To determine the stability of both sugar-containing and sugar-free rufinamide suspensions over a 90-day period. A suspension of rufinamide 40 mg/mL was prepared by grinding twelve 400-mg tablets of rufinamide tablets in a glass mortar. Sixty milliliters of Ora-Plus and 60 mL of either Ora-Sweet or Ora-Sweet SF (sugar free) were mixed and added to the powder to make a final volume of 120 mL. Three identical samples of each formulation were prepared and placed in 60-mL amber plastic bottles and were stored at room temperature. A 1-mL sample was withdrawn from each of the 6 bottles with a micropipette immediately after preparation and at 7, 14, 28, 56, and 90 days. After further dilution to an expected concentration of 0.4 mg/mL, the samples were assayed using high-performance liquid chromatography. Stability was defined as the retention of at least 90% of the initial concentration. At least 90% of the initial rufinamide concentration remained throughout the 90-day study period in both preparations. There were no detectable changes in color, odor, taste, and pH and no visible microbial growth. Extemporaneously compounded suspensions of rufinamide 40 mg/mL in a 1:1 mixture of Ora-Plus and Ora-Sweet or Ora-Sweet SF were stable for at least 90 days when stored in 59-mL amber polypropylene plastic bottles at room temperature.

  10. Flow of Dense Granular Suspensions on an Inclined Plane

    Science.gov (United States)

    Bonnoit, C.; Lanuza, J.; Lindner, A.; Clément, E.

    2008-07-01

    We investigate the flow behavior of dense granular suspensions, by the use of an inclined plane. The suspensions are prepared at high packing fractions and consist of spherical non-Brownian particles density matched with the suspending fluid. On the inclined plane, we perform a systematic study of the surface velocity as a function of the layer thickness for various flow rates and tilt angles. We perform measurements on a classical rheometer (parallel-plate rheometer) that is shown to be in good agreement with existing models, up to a volume fraction of 50%. Comparing these results, we show that the flow on an inclined plane can, up to a volume fraction of 50%, indeed be described by a purely viscous model in agreement with the results from classical rheometry.

  11. Evaluating damping elements for two-stage suspension vehicles

    Directory of Open Access Journals (Sweden)

    Ronald M. Martinod R.

    2012-01-01

    Full Text Available The technical state of the damping elements for a vehicle having two-stage suspension was evaluated by using numerical models based on the multi-body system theory; a set of virtual tests used the eigenproblem mathematical method. A test was developed based on experimental modal analysis (EMA applied to a physical system as the basis for validating the numerical models. The study focused on evaluating vehicle dynamics to determine the influence of the dampers’ technical state in each suspension state.

  12. Determining Quiescent Colloidal Suspension Viscosities Using the Green-Kubo Relation and Image-Based Stress Measurements

    Science.gov (United States)

    Lin, Neil Y. C.; Bierbaum, Matthew; Cohen, Itai

    2017-09-01

    By combining confocal microscopy and stress assessment from local structural anisotropy, we directly measure stresses in 3D quiescent colloidal liquids. Our noninvasive and nonperturbative method allows us to measure forces ≲50 fN with a small and tunable probing volume, enabling us to resolve the stress fluctuations arising from particle thermal motions. We use the Green-Kubo relation to relate these measured stress fluctuations to the bulk Brownian viscosity at different volume fractions, comparing against simulations and conventional rheometry measurements. We find that the Green-Kubo analysis gives excellent agreement with these prior results, suggesting that similar methods could be applied to investigations of local flow properties in many poorly understood far-from-equilibrium systems, including suspensions that are glassy, strongly sheared, or highly confined.

  13. Universal behaviour of silica suspensions gelled under shear

    International Nuclear Information System (INIS)

    Hanley, H J M; Muzny, C D; Bartlett, J; Drabarek, E

    2007-01-01

    The shear-influenced gelation of three aqueous suspensions consisting of silica particles of nominal diameter 7, 12 and 24 nm, respectively, is reported. It is shown that the viscosity/stress of a gelling system increases with time after gel initiation, reaches a maximum, then falls to a plateau value. A very simple relation between this maximum stress and the precursor volume fraction is verified experimentally

  14. An efficient sensitivity analysis method for modified geometry of Macpherson suspension based on Pearson correlation coefficient

    Science.gov (United States)

    Shojaeefard, Mohammad Hasan; Khalkhali, Abolfazl; Yarmohammadisatri, Sadegh

    2017-06-01

    The main purpose of this paper is to propose a new method for designing Macpherson suspension, based on the Sobol indices in terms of Pearson correlation which determines the importance of each member on the behaviour of vehicle suspension. The formulation of dynamic analysis of Macpherson suspension system is developed using the suspension members as the modified links in order to achieve the desired kinematic behaviour. The mechanical system is replaced with an equivalent constrained links and then kinematic laws are utilised to obtain a new modified geometry of Macpherson suspension. The equivalent mechanism of Macpherson suspension increased the speed of analysis and reduced its complexity. The ADAMS/CAR software is utilised to simulate a full vehicle, Renault Logan car, in order to analyse the accuracy of modified geometry model. An experimental 4-poster test rig is considered for validating both ADAMS/CAR simulation and analytical geometry model. Pearson correlation coefficient is applied to analyse the sensitivity of each suspension member according to vehicle objective functions such as sprung mass acceleration, etc. Besides this matter, the estimation of Pearson correlation coefficient between variables is analysed in this method. It is understood that the Pearson correlation coefficient is an efficient method for analysing the vehicle suspension which leads to a better design of Macpherson suspension system.

  15. Equation of state of charged latex suspensions

    International Nuclear Information System (INIS)

    Reus, Valerie

    1995-01-01

    We measured the osmotic pressure of charged bromo-polystyrene particles suspensions in the dilute System (0,01-10% in volume fraction). The typical range of differences in water heights varies from one millimeter to a few centimeters. When particles are polydisperse, samples remain always sols but if particles are monodisperse, they can form supramolecular crystals stabilized by electrostatic repulsions. These crystals exist only when the ionic force is very low, about one μmole/l. We determined the structure of these assemblies by light and X-ray scattering as function of the volume fraction. At low volume fractions, crystals adopt a body centered cubic structure; when the concentration increases, they become more compact and we observe face centered cubic structures. After shearing, defects may appear and two dimensional hexagonal structures can be found. This type of study of the osmotic pressure versus distance (in the range 300 nm) is equivalent to a highly precise atomic force measurement, since it allows detection of forces as small as 10 -11 -10 -12 N. (author) [fr

  16. Active Control of Suspension Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

  17. Fumed and Precipitated Hydrophilic Silica Suspension Gels in Mineral Oil: Stability and Rheological Properties

    Directory of Open Access Journals (Sweden)

    Yoshiki Sugino

    2017-08-01

    Full Text Available Hydrophilic fumed silica (FS and precipitated silica (PS powders were suspended in mineral oil; increasing the silica volume fraction (φ in the suspension led to the formation of sol, pre-gel, and gel states. Gelation took place at lower φ values in the FS than the PS suspension because of the lower silanol density on the FS surface. The shear stresses and dynamic moduli of the FS and PS suspensions were measured as a function of φ. Plots of the apparent shear viscosity against shear rate depended on φ and the silica powder. The FS suspensions in the gel state exhibited shear thinning, followed by a weak shear thickening or by constant viscosity with an increasing shear rate. In contrast, the PS suspensions in the gel state showed shear thinning, irrespective of φ. The dynamic moduli of the pre-gel and gel states were dependent on the surface silanol density: at a fixed φ, the storage modulus G′ in the linear viscoelasticity region was larger for the FS than for the PS suspension. Beyond the linear region, the G′ of the PS suspensions showed strain hardening and the loss modulus G″ of the FS and PS suspensions exhibited weak strain overshoot.

  18. Numerical homogenization on approach for stokesian suspensions.

    Energy Technology Data Exchange (ETDEWEB)

    Haines, B. M.; Berlyand, L. V.; Karpeev, D. A. (Mathematics and Computer Science); (Department of Mathematics, Pennsylvania State Univ.)

    2012-01-20

    In this technical report we investigate efficient methods for numerical simulation of active suspensions. The prototypical system is a suspension of swimming bacteria in a Newtonian fluid. Rheological and other macroscopic properties of such suspensions can differ dramatically from the same properties of the suspending fluid alone or of suspensions of similar but inactive particles. Elongated bacteria, such as E. coli or B. subtilis, swim along their principal axis, propelling themselves with the help of flagella, attached at the anterior of the organism and pushing it forward in the manner of a propeller. They interact hydrodynamically with the surrounding fluid and, because of their asymmetrical shape, have the propensity to align with the local flow. This, along with the dipolar nature of bacteria (the two forces a bacterium exerts on a fluid - one due to self-propulsion and the other opposing drag - have equal magnitude and point in opposite directions), causes nearby bacteria to tend to align, resulting in a intermittent local ordering on the mesoscopic scale, which is between the microscopic scale of an individual bacterium and the macroscopic scale of the suspension (e.g., its container). The local ordering is sometimes called a collective mode or collective swimming. Thanks to self-propulsion, collective modes inject momentum into the fluid in a coherent way. This enhances the local strain rate without changing the macroscopic stress applied at the boundary of the container. The macroscopic effective viscosity of the suspension is defined roughly as the ratio of the applied stress to the bulk strain rate. If local alignment and therefore local strain-rate enhancement, are significant, the effective viscosity can be appreciably lower than that of the corresponding passive suspension or even of the surrounding fluid alone. Indeed, a sevenfold decrease in the effective viscosity was observed in experiments with B. subtilis. More generally, local collective

  19. Effect of facial material softness and applied force on face mask dead volume, face mask seal, and inhaled corticosteroid delivery through an idealized infant replica.

    Science.gov (United States)

    Carrigy, Nicholas B; O'Reilly, Connor; Schmitt, James; Noga, Michelle; Finlay, Warren H

    2014-08-01

    During the aerosol delivery device design and optimization process, in vitro lung dose (LD) measurements are often performed using soft face models, which may provide a more clinically relevant representation of face mask dead volume (MDV) and face mask seal (FMS) than hard face models. However, a comparison of MDV, FMS, and LD for hard and soft face models is lacking. Metal, silicone, and polyurethane represented hard, soft, and very soft facial materials, respectively. MDV was measured using a water displacement technique. FMS was measured using a valved holding chamber (VHC) flow rate technique. The LD of beclomethasone dipropionate (BDP) delivered via a 100-μg Qvar® pressurized metered dose inhaler with AeroChamber Plus® Flow-Vu® VHC and Small Mask, defined as that which passes through the nasal airways of the idealized infant geometry, was measured using a bias tidal flow system with a filter. MDV, FMS, and LD were measured at 1.5 lb and 3.5 lb of applied force. A mathematical model was used to predict LD based on experimental measurements of MDV and FMS. Experimental BDP LD measurements for ABS, silicone, and polyurethane at 1.5 lb were 0.9 (0.6) μg, 2.4 (1.9) μg, and 19.3 (0.9) μg, respectively. At 3.5 lb, the respective LD was 10.0 (1.5) μg, 13.8 (1.4) μg, and 14.2 (0.9) μg. Parametric analysis with the mathematical model showed that differences in FMS between face models had a greater impact on LD than differences in MDV. The use of soft face models resulted in higher LD than hard face models, with a greater difference at 1.5 lb than at 3.5 lb. A lack of a FMS led to decreased dose consistency; therefore, a sealant should be used when measuring LD with a hard ABS or soft silicone face model at 1.5 lb of applied force or less.

  20. NUMERICAL RESEARCH ON THE THREE-DIMENSIONAL FIBER ORIENTATION DISTRIBUTION IN PLANAR SUSPENSION FLOWS

    Directory of Open Access Journals (Sweden)

    Qihua Zhang

    Full Text Available Abstract To describe flow-induced fiber orientation, the Fokker-Planck equation is widely applied in the processing of composites and fiber suspensions. The analytical solution only exists when the Péclet number is infinite. So developing a numerical method covering a full range of Péclet number is of great significance. To accurately solve the Fokker-Planck equation, a numerical scheme based on the finite volume method is developed. Using spherical symmetry, the boundary is discretized and formulated into a cyclic tridiagonal matrix which is further solved by the CTDMA algorithm. To examine its validity, benchmark tests over a wide range of Péclet number are performed in a simple shear flow. For Pe=∞, the results agree well with the analytical solutions. For the other Pe numbers, the results are compared to results available in the literature. The tests show that this algorithm is accurate, stable, and globally conservative. Furthermore, this algorithm can be extended and used to predict the three-dimensional orientation distribution of complex suspension flows.

  1. Four-Wheel Vehicle Suspension System

    Science.gov (United States)

    Bickler, Donald B.

    1990-01-01

    Four-wheel suspension system uses simple system of levers with no compliant components to provide three-point suspension of chassis of vehicle while maintaining four-point contact with uneven terrain. Provides stability against tipping of four-point rectangular base, without rocking contact to which rigid four-wheel frame susceptible. Similar to six-wheel suspension system described in "Articulated Suspension Without Springs" (NPO-17354).

  2. Heavy vehicle pitch dynamics and suspension tuning

    OpenAIRE

    Cao, Dongpu; Rakheja, Subhash; Su, Chun-Yi

    2008-01-01

    The influence of suspension tuning of passenger cars on bounce and pitch ride performance has been explored in a number of studies, while only minimal efforts have been made for establishing similar rules for heavy vehicles. This study aims to explore pitch dynamics and suspension tunings of a two-axle heavy vehicle with unconnected suspension, which could also provide valuable information for heavy vehicles with coupled suspensions. Based on a generalised pitch-plane model of a two-axle heav...

  3. Suspension-Firing of Biomass

    DEFF Research Database (Denmark)

    Shafique Bashir, Muhammad; Jensen, Peter Arendt; Frandsen, Flemming

    2012-01-01

    This paper is the second of two papers, describing probe measurements of deposit buildup and removal (shedding), conducted in a 350 MWth suspension-fired boiler, firing straw and wood. Investigations of deposit buildup and shedding have been made by use of an advanced online deposit probe and a s...

  4. Suspension-Firing of Biomass

    DEFF Research Database (Denmark)

    Bashir, Muhammad Shafique; Jensen, Peter Arendt; Frandsen, Flemming

    2012-01-01

    This paper is Part 1 in a series of two describing probe measurements of deposit build-up and removal (shedding) in a 350 MWth suspension boiler, firing straw and wood. The influence of fuel type (straw share in wood), probe exposure time, probe surface temperature (500, 550, and 600 °C), and flu...

  5. Nonlinear models of suspension bridges

    Czech Academy of Sciences Publication Activity Database

    Malík, Josef

    2006-01-01

    Roč. 321, č. 2 (2006), s. 828-850 ISSN 0022-247X Institutional research plan: CEZ:AV0Z30860518 Keywords : suspension bridges * principle of minimum energy Subject RIV: BA - General Mathematics Impact factor: 0.758, year: 2006

  6. Fracture in Kaolinite clay suspensions

    Science.gov (United States)

    Kosgodagan Acharige, Sebastien; Jerolmack, Douglas J.; Arratia, Paulo E.

    2017-11-01

    Clay minerals are involved in many natural (landslides, river channels) and industrial processes (ceramics, cosmetics, oil recovery). They are plate shaped charged colloids and exhibit different flow properties than simpler colloids when suspended in a liquid such as thixotropy and shear-banding. kaolinite platelets are non-swelling, meaning that the stacks formed by the platelets do not have water layers, and thus the suspension does not have a sol-gel transition. However, it has been shown that kaolinite suspensions possesses a non-zero yield stress even at low concentrations, indicating that the particles arrange themselves in a structure through attractive interactions. Here, we experimentally investigate the sedimentation of kaolinite suspensions in a Hele-Shaw cell. The sedimentation of these dilute suspensions can display solid behavior like fracture, revealed in cross-polarized light, which is linked to the failure of the weakly-bonded structure (typical yield stress 10-2 Pa). By changing the interaction potential of the particles (by sonication or introducing salts), we show through these sedimentation experiments, how the fracture pattern can be avoided. Research was sponsored by the Army Research Laboratory and was accomplished under Grant Number 569074.

  7. Progress report on nuclear science and technology in China (Vol.3). Proceedings of academic annual meeting of China Nuclear Society in 2013, No.9--nuclear technology applied in industry sub-volume

    International Nuclear Information System (INIS)

    2014-05-01

    Progress report on nuclear science and technology in China (Vol. 3) includes 35 articles which are communicated on the third national academic annual meeting of China Nuclear Society. There are 10 books totally. This is the ninth one, the content is about nuclear technology applied in industry sub-volume

  8. 49 CFR 570.8 - Suspension systems.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Suspension systems. 570.8 Section 570.8 Transportation Other Regulations Relating to Transportation (Continued) NATIONAL HIGHWAY TRAFFIC SAFETY... Pounds or Less § 570.8 Suspension systems. (a) Suspension condition. Ball joint seals shall not be cut or...

  9. 49 CFR 570.61 - Suspension system.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 6 2010-10-01 2010-10-01 false Suspension system. 570.61 Section 570.61... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION VEHICLE IN USE INSPECTION STANDARDS Vehicles With GVWR of More Than 10,000 Pounds § 570.61 Suspension system. (a) Suspension condition. Ball joint seals shall not be cut...

  10. Quadruple suspension design for Advanced LIGO

    International Nuclear Information System (INIS)

    Robertson, N A; Cagnoli, G; Crooks, D R M; Elliffe, E; Faller, J E; Fritschel, P; Gossler, S; Grant, A; Heptonstall, A; Hough, J; Lueck, H; Mittleman, R; Perreur-Lloyd, M; Plissi, M V; Rowan, S; Shoemaker, D H; Sneddon, P H; Strain, K A; Torrie, C I; Ward, H; Willems, P

    2002-01-01

    In this paper, we describe the conceptual design for the suspension system for the test masses for Advanced LIGO, the planned upgrade to LIGO, the US laser interferometric gravitational-wave observatory. The design is based on the triple pendulum design developed for GEO 600 - the German/UK interferometric gravitational wave detector. The GEO design incorporates fused silica fibres of circular cross-section attached to the fused silica mirror (test mass) in the lowest pendulum stage, in order to minimize the thermal noise from the pendulum modes. The damping of the low-frequency modes of the triple pendulum is achieved by using co-located sensors and actuators at the highest mass of the triple pendulum. Another feature of the design is that global control forces acting on the mirrors, used to maintain the output of the interferometer on a dark fringe, are applied via a triple reaction pendulum, so that these forces can be implemented via a seismically isolated platform. These techniques have been extended to meet the more stringent noise levels planned for in Advanced LIGO. In particular, the Advanced LIGO baseline design requires a quadruple pendulum with a final stage consisting of a 40 kg sapphire mirror, suspended on fused silica ribbons or fibres. The design is chosen to aim to reach a target noise contribution from the suspension corresponding to a displacement sensitivity of 10 -19 m Hz -1/2 at 10 Hz at each of the test masses

  11. Viscosity of diluted suspensions of vegetal particles in water

    Directory of Open Access Journals (Sweden)

    Szydłowska Adriana

    2017-01-01

    Full Text Available Viscosity and rheological behaviour of sewage as well as sludge are essential while designing apparatuses and operations employed in the sewage treatment process and its processing. With reference to these substances, the bio-suspensions samples of three size fractions ((i 150÷212 μm, (ii 106÷150 μm and (iii below106 μm of dry grass in water with solid volume fraction 8%, 10% and 11% were prepared. After twenty four hours prior to their preparation time, the suspension samples underwent rheometeric measurements with the use of a rotational rheometer with coaxial cylinders. On the basis of the obtained results, flow curves were plotted and described with both the power model and Herschel-Bulkley model. Moreover, the viscosity of the studied substances was determined that allowed to conclude that the studied bio-suspensions display features of viscoelastic fluids. The experimentally established viscosity was compared to the calculated one according to Manley and Manson equation, recommended in the literature. It occurred that the measured viscosity values substantially exceed the calculation viscosity values, even by 105 times. The observations suggest that it stems from water imbibition of fibrous vegetal particles, which causes their swelling and decreases the amount of liquid phase in the suspension.

  12. Two-Dimensional Fuzzy Sliding Mode Control of a Field-Sensed Magnetic Suspension System

    Directory of Open Access Journals (Sweden)

    Jen-Hsing Li

    2014-01-01

    Full Text Available This paper presents the two-dimensional fuzzy sliding mode control of a field-sensed magnetic suspension system. The fuzzy rules include both the sliding manifold and its derivative. The fuzzy sliding mode control has advantages of the sliding mode control and the fuzzy control rules are minimized. Magnetic suspension systems are nonlinear and inherently unstable systems. The two-dimensional fuzzy sliding mode control can stabilize the nonlinear systems globally and attenuate chatter effectively. It is adequate to be applied to magnetic suspension systems. New design circuits of magnetic suspension systems are proposed in this paper. ARM Cortex-M3 microcontroller is utilized as a digital controller. The implemented driver, sensor, and control circuits are simpler, more inexpensive, and effective. This apparatus is satisfactory for engineering education. In the hands-on experiments, the proposed control scheme markedly improves performances of the field-sensed magnetic suspension system.

  13. Vibration control of an energy regenerative seat suspension with variable external resistance

    Science.gov (United States)

    Ning, Donghong; Sun, Shuaishuai; Du, Haiping; Li, Weihua; Zhang, Nong

    2018-06-01

    In this paper, an energy regenerative seat suspension with a variable external resistance is proposed and built, and a semi-active controller for its vibration control is also designed and validated. The energy regenerative seat suspension is built with a three-phase generator and a gear reducer, which are installed in the scissors structure centre of the seat suspension, and the vibration energy is directly harvested from the rotary movement of suspension's scissors structure. The electromagnetic torque of the semi-active seat suspension actuator is controlled by an external variable resistor. An integrated model including the seat suspension's kinematics and the generator is built and proven to match the test result very well. A simplified experimental phenomenon model is also built based on the test results for the controller design. A state feedback H∞ controller is proposed for the regenerative seat suspension's semi-active vibration control. The proposed regenerative seat suspension and its controller are validated with both simulations and experiments. A well-tuned passive seat suspension is applied to evaluate the regenerative seat's performance. Based on ISO 2631-1, the frequency-weighted root mean square (FW-RMS) acceleration of the proposed seat suspension has a 22.84% reduction when compared with the passive one, which indicates the improvement of ride comfort. At the same time, the generated RMS power is 1.21 W. The proposed regenerative seat suspension can greatly improve the driver's ride comfort and has the potential to be developed to a self-powered semi-active system.

  14. Suspensions with reduced violin string modes

    International Nuclear Information System (INIS)

    Lee, B H; Ju, L; Blair, D G

    2006-01-01

    We discuss the possibility of significantly reducing the number and Q-factor of violin string modes in the mirror suspension. Simulations of a bar-flexure suspension and an orthogonal ribbon have shown a reduction in the number of violin string modes when compared to a normal ribbon suspension. By calculating the expected suspension thermal noise, we find that the orthogonal ribbon provides a promising suspension alternative. A lower number of violin modes oscillating in the direction of the laser and a reduction in violin mode peak values of at least 23dB can be achieved with a slight increase in thermal noise above 40Hz

  15. Suspensions with reduced violin string modes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, B H; Ju, L; Blair, D G [School of Physics, University of Western Australia, Crawley 6009, WA (Australia)

    2006-03-02

    We discuss the possibility of significantly reducing the number and Q-factor of violin string modes in the mirror suspension. Simulations of a bar-flexure suspension and an orthogonal ribbon have shown a reduction in the number of violin string modes when compared to a normal ribbon suspension. By calculating the expected suspension thermal noise, we find that the orthogonal ribbon provides a promising suspension alternative. A lower number of violin modes oscillating in the direction of the laser and a reduction in violin mode peak values of at least 23dB can be achieved with a slight increase in thermal noise above 40Hz.

  16. Model-assisted measurements of suspension-feeding flow velocities.

    Science.gov (United States)

    Du Clos, Kevin T; Jones, Ian T; Carrier, Tyler J; Brady, Damian C; Jumars, Peter A

    2017-06-01

    Benthic marine suspension feeders provide an important link between benthic and pelagic ecosystems. The strength of this link is determined by suspension-feeding rates. Many studies have measured suspension-feeding rates using indirect clearance-rate methods, which are based on the depletion of suspended particles. Direct methods that measure the flow of water itself are less common, but they can be more broadly applied because, unlike indirect methods, direct methods are not affected by properties of the cleared particles. We present pumping rates for three species of suspension feeders, the clams Mya arenaria and Mercenaria mercenaria and the tunicate Ciona intestinalis , measured using a direct method based on particle image velocimetry (PIV). Past uses of PIV in suspension-feeding studies have been limited by strong laser reflections that interfere with velocity measurements proximate to the siphon. We used a new approach based on fitting PIV-based velocity profile measurements to theoretical profiles from computational fluid dynamic (CFD) models, which allowed us to calculate inhalant siphon Reynolds numbers ( Re ). We used these inhalant Re and measurements of siphon diameters to calculate exhalant Re , pumping rates, and mean inlet and outlet velocities. For the three species studied, inhalant Re ranged from 8 to 520, and exhalant Re ranged from 15 to 1073. Volumetric pumping rates ranged from 1.7 to 7.4 l h -1 for M . arenaria , 0.3 to 3.6 l h -1 for M . m ercenaria and 0.07 to 0.97 l h -1 for C . intestinalis We also used CFD models based on measured pumping rates to calculate capture regions, which reveal the spatial extent of pumped water. Combining PIV data with CFD models may be a valuable approach for future suspension-feeding studies. © 2017. Published by The Company of Biologists Ltd.

  17. Generating an Engineered Adipose Tissue Flap Using an External Suspension Device.

    Science.gov (United States)

    Wan, Jinlin; Dong, Ziqing; Lei, Chen; Lu, Feng

    2016-07-01

    The tissue-engineering chamber technique can generate large volumes of adipose tissue, which provides a potential solution for the complex reconstruction of large soft-tissue defects. However, major drawbacks of this technique are the foreign-body reaction and the volume limitation imposed by the chamber. In this study, the authors developed a novel tissue-engineering method using a specially designed external suspension device that generates an optimized volume of adipose flap and avoids the implantation of foreign material. The rabbits were processed using two different tissue-engineering methods, the external suspension device technique and the traditional tissue-engineering chamber technique. The adipose flaps generated by the external suspension device had a normal adipose tissue structure that was as good as that generated by the traditional tissue-engineering chamber, but the flap volume was much larger. The final volume of the engineered adipose flap grew between weeks 0 and 36 from 5.1 ml to 30.7 ml in the traditional tissue-engineering chamber group and to 80.5 ml in the external suspension device group. During the generation process, there were no marked differences between the two methods in terms of structural and cellular changes of the flap, except that the flaps in the traditional tissue-engineering chamber group had a thicker capsule at the early stage. In addition, the enlarged flaps generated by the external suspension device could be reshaped into specific shapes by the implant chamber. This minimally invasive external suspension device technique can generate large-volume adipose flaps. Combined with a reshaping method, this technique should facilitate clinical application of adipose tissue engineering.

  18. Viscosity of aqueous and cyanate ester suspensions containing alumina nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, Katherine [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    be the cause of the viscosity reduction. The flow behavior of alumina particles in water and BECy is markedly different. Aqueous alumina suspensions are shear thinning at all alumina loadings and capable of 50 vol% loading before losing fluidity whereas BECy/alumina suspensions show Newtonian behavior up to 5 vol%, and above 5 vol% show shear thinning at all shear rates. Highly loaded suspensions (i.e. 20vol% alumina) exhibit shear thinning at low and moderate shear rates and shear thickening at higher shear rates. The maximum particle loading for a fluid suspension, in this case, appears to be about 20 vol%. The difference in the viscosity of these suspensions must be related to the solvent-particle interactions for each system. The reason is not exactly known, but there are some notable differences between BECy and water. Water molecules are {approx}0.28 nm in length and highly hydrogen bonded with a low viscosity (1 mPa's) whereas in the cyanate ester (BECy) system, the solvent molecule is about 1.2 nm, in the largest dimension, with surfaces of varied charge distribution throughout the molecule. The viscosity of the monomer is also reasonably low for organic polymer precursor, about 7 mPa's. Nanoparticles in water tend to agglomerate and form flocs which are broken with the shear force applied during viscosity measurement. The particle-particle interaction is very important in this system. In BECy, the particles appear to be well dispersed and not as interactive. The solvent-particle interaction appears to be most important. It is not known exactly how the alumina particles interact with the monomer, but NMR suggests hydrogen bonding. These hydrogen bonds between the particle and monomer could very well affect the viscosity. A conclusion that can be reached in this work is that the presence of hydroxyl groups on the surface of the alumina particles is significant and seems to affect the interactions between other particles and the solvent. Thus, the

  19. Velocity and size distribution measurement of suspension droplets using PDPA technique

    Science.gov (United States)

    Amiri, Shahin; Akbarnozari, Ali; Moreau, Christian; Dolatabadi, Ali

    2015-11-01

    The creation of fine and uniform droplets from a bulk of liquid is a vital process in a variety of engineering applications, such as atomization in suspension plasma spray (SPS) in which the submicron coating materials are injected to the plasma gas through the suspension droplets. The size and velocity of these droplets has a great impact on the interaction of the suspension with the gas flow emanating from a plasma torch and can consequently affect the mechanical and chemical properties of the resultant coatings. In the current study, an aqueous suspension of small glass particles (2-8 μm) was atomized by utilizing an effervescent atomizer of 1 mm orifice diameter which involves bubbling gas (air) directly into the liquid stream. The gas to liquid ratio (GLR) was kept constant at 6% throughout this study. The mass concentration of glass particles varied in the range between 0.5 to 5% in order to investigate the effect of suspension viscosity and surface tension on the droplet characteristics, such as velocity and size distributions. These characteristics were simultaneously measured by using a non-intrusive optical technique, Phase Doppler Particle Anemometry (PDPA), which is based on the light signal scattered from the droplets moving in a measurement volume. The velocity and size distribution of suspension droplets were finally compared to those of distilled water under identical conditions. The results showed a different atomization behaviors due to the reduction in surface tension of the suspension spray.

  20. Particle Suspension Mechanisms - Supplemental Material

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, M B

    2011-03-03

    This supplemental material provides a brief introduction to particle suspension mechanisms that cause exfoliated skin cells to become and remain airborne. The material presented here provides additional context to the primary manuscript and serves as background for designing possible future studies to assess the impact of skin cells as a source of infectious aerosols. This introduction is not intended to be comprehensive and interested readers are encouraged to consult the references cited.

  1. Robust Tensioned Kevlar Suspension Design

    Science.gov (United States)

    Young, Joseph B.; Naylor, Bret J.; Holmes, Warren A.

    2012-01-01

    One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar.

  2. Structure and rheology of nanoparticle–polymer suspensions

    KAUST Repository

    Srivastava, Samanvaya

    2012-01-01

    Structure and rheology of oligomer-tethered nanoparticles suspended in low molecular weight polymeric host are investigated at various particle sizes and loadings. Strong curvature effects introduced by the small size of the nanoparticle cores are found to be important for understanding both the phase stability and rheology of the materials. Small angle X-ray scattering (SAXS) and transmission electron microscopy measurements indicate that PEG-SiO 2/PEG suspensions are more stable against phase separation and aggregation than expected from theory for interacting brushes. SAXS and rheology measurements also reveal that at high particle loadings, the stabilizing oligomer brush is significantly compressed and produces jamming in the suspensions. The jamming transition is accompanied by what appears to be a unique evolution in the transient suspension rheology, along with large increments in the zero-shear, Newtonian viscosity. The linear and nonlinear flow responses of the jammed suspensions are discussed in the framework of the Soft Glassy Rheology (SGR) model, which is shown to predict many features that are consistent with experimental observations, including a two-step relaxation following flow cessation and a facile method for determining the shear-thinning coefficient from linear viscoelastic measurements. Finally, we show that the small sizes of the particles have a significant effect on inter-particle interactions and rheology, leading to stronger deviations from expectations based on planar brushes and hard-sphere suspension theories. In particular, we find that in the high volume fraction limit, tethered nanoparticles interact in their host polymer through short-range forces, which are more analogous to those between soft particles than between spherical polymer brushes. © 2012 The Royal Society of Chemistry.

  3. Polymorphism in Bacterial Flagella Suspensions

    Science.gov (United States)

    Schwenger, Walter J.

    Bacterial flagella are a type of biological polymer studied for its role in bacterial motility and the polymorphic transitions undertaken to facilitate the run and tumble behavior. The naturally rigid, helical shape of flagella gives rise to novel colloidal dynamics and material properties. This thesis studies methods in which the shape of bacterial flagella can be controlled using in vitro methods and the changes the shape of the flagella have on both single particle dynamics and bulk material properties. We observe individual flagellum in both the dilute and semidilute regimes to observe the effects of solvent condition on the shape of the filament as well as the effect the filament morphology has on reptation through a network of flagella. In addition, we present rheological measurements showing how the shape of filaments effects the bulk material properties of flagellar suspensions. We find that the individual particle dynamics in suspensions of flagella can vary with geometry from needing to reptate linearly via rotation for helical filaments to the prevention of long range diffusion for block copolymer filaments. Similarly, for bulk material properties of flagella suspensions, helical geometries show a dramatic enhancement in elasticity over straight filaments while block copolymers form an elastic gel without the aid of crosslinking agents.

  4. Sedimentation and gravitational instability of Escherichia coli Suspension

    Science.gov (United States)

    Salin, Dominique; Douarche, Carine

    2017-11-01

    The successive runs and tumbles of Escherichia coli bacteria provide an active matter suspension of rod-like particles with a large swimming, Brownian like, diffusion. As opposed to inactive elongated particles, this diffusion prevents clustering of the particles and hence instability in the gravity field. We measure the time dependent E . coli concentration profile during their sedimentation. After some hours, due to the dioxygen consumption, a motile / non-motile front forms leading to a Rayleigh-Taylor type gravitational instability. Analysing both sedimentation and instability in the framework of active particle suspensions, we can measure the relevant bacteria hydrodynamic characteristics such as its single particle sedimentation velocity and its hindrance volume. Comparing these quantities to the ones of equivalent passive particles (ellipsoid, rod) we tentatively infer the effective shape and size of the bacteria involved in its buoyancy induced advection and diffusion. Laboratoire FAST University Paris Saclay France.

  5. The Effect of Polymer Content on the Non-Newtonian Behavior of Acetaminophen Suspension

    Science.gov (United States)

    Moghimipour, Eskandar; Kouchak, Maryam; Salimi, Anayatollah; Bahrampour, Saeed; Handali, Somayeh

    2013-01-01

    Acetaminophen is used as an analgesic and antipyretic agent. The aim of the study was evaluation of the effect of different polymers on rheological behavior of acetaminophen suspension. In order to achieve controlled flocculation, sodium chloride was added. Then structural vehicles such as carboxymethyl cellulose (CMC), polyvinyl pyrrolidone (PVP), tragacanth, and magnesium aluminum silicate (Veegum) were evaluated individually and in combination. Physical stability parameters such as sedimentation volume (F), redispersibility (n), and growth of crystals of the suspensions were determined. Also, the rheological properties of formulations were studied. The results of this study showed that the combination of suspending agents had the most physical stability and pseudoplastic behavior with some degree of thixotropy. Viscosity of suspensions was increased by adding NaCl 0.02%. Presence of PVP is necessary for improving rheological behavior of suspensions by NaCl. This may be related to the cross-linking between the carbonyl group in the PVP segment and Na+ ions. PMID:24109512

  6. Measurement of the effective refractive index of a turbid colloidal suspension using light refraction

    International Nuclear Information System (INIS)

    Reyes-Coronado, A; Garcia-Valenzuela, A; Sanchez-Perez, C; Barrera, R G

    2005-01-01

    We propose and analyse a simple method to measure simultaneously the real and imaginary parts of the effective refractive index of a turbid suspension of particles. The method is based on measurements of the angle of refraction and transmittance of a laser beam that traverses a hollow glass prism filled with a colloidal suspension. We provide a comprehensive assessment of the method. It can offer high sensitivity while still being simple to interpret. We present results of experiments using an optically turbid suspension of polystyrene particles and compare them with theoretical predictions. We also report experimental evidence showing that the refractive behaviour of the diffuse component of light coming from a suspension depends on the volume fraction of the colloidal particles

  7. Non-linear dielectric spectroscopy of microbiological suspensions

    Science.gov (United States)

    Treo, Ernesto F; Felice, Carmelo J

    2009-01-01

    Background Non-linear dielectric spectroscopy (NLDS) of microorganism was characterized by the generation of harmonics in the polarization current when a microorganism suspension was exposed to a sinusoidal electric field. The biological nonlinear response initially described was not well verified by other authors and the results were susceptible to ambiguous interpretation. In this paper NLDS was performed to yeast suspension in tripolar and tetrapolar configuration with a recently developed analyzer. Methods Tripolar analysis was carried out by applying sinusoidal voltages up to 1 V at the electrode interface. Tetrapolar analysis was carried on with sinusoidal field strengths from 0.1 V cm-1 to 70 V cm-1. Both analyses were performed within a frequency range from 1 Hz through 100 Hz. The harmonic amplitudes were Fourier-analyzed and expressed in dB. The third harmonic, as reported previously, was investigated. Statistical analysis (ANOVA) was used to test the effect of inhibitor an activator of the plasma membrane enzyme in the measured response. Results No significant non-linearities were observed in tetrapolar analysis, and no observable changes occurred when inhibitor and activator were added to the suspension. Statistical analysis confirmed these results. When a pure sinus voltage was applied to an electrode-yeast suspension interface, variations higher than 25 dB for the 3rd harmonic were observed. Variation higher than 20 dB in the 3rd harmonics has also been found when adding an inhibitor or activator of the membrane-bounded enzymes. These variations did not occur when the suspension was boiled. Discussion The lack of result in tetrapolar cells suggest that there is no, if any, harmonic generation in microbiological bulk suspension. The non-linear response observed was originated in the electrode-electrolyte interface. The frequency and voltage windows observed in previous tetrapolar analysis were repeated in the tripolar measurements, but maximum were not

  8. Non-linear dielectric spectroscopy of microbiological suspensions

    Directory of Open Access Journals (Sweden)

    Felice Carmelo J

    2009-09-01

    Full Text Available Abstract Background Non-linear dielectric spectroscopy (NLDS of microorganism was characterized by the generation of harmonics in the polarization current when a microorganism suspension was exposed to a sinusoidal electric field. The biological nonlinear response initially described was not well verified by other authors and the results were susceptible to ambiguous interpretation. In this paper NLDS was performed to yeast suspension in tripolar and tetrapolar configuration with a recently developed analyzer. Methods Tripolar analysis was carried out by applying sinusoidal voltages up to 1 V at the electrode interface. Tetrapolar analysis was carried on with sinusoidal field strengths from 0.1 V cm-1 to 70 V cm-1. Both analyses were performed within a frequency range from 1 Hz through 100 Hz. The harmonic amplitudes were Fourier-analyzed and expressed in dB. The third harmonic, as reported previously, was investigated. Statistical analysis (ANOVA was used to test the effect of inhibitor an activator of the plasma membrane enzyme in the measured response. Results No significant non-linearities were observed in tetrapolar analysis, and no observable changes occurred when inhibitor and activator were added to the suspension. Statistical analysis confirmed these results. When a pure sinus voltage was applied to an electrode-yeast suspension interface, variations higher than 25 dB for the 3rd harmonic were observed. Variation higher than 20 dB in the 3rd harmonics has also been found when adding an inhibitor or activator of the membrane-bounded enzymes. These variations did not occur when the suspension was boiled. Discussion The lack of result in tetrapolar cells suggest that there is no, if any, harmonic generation in microbiological bulk suspension. The non-linear response observed was originated in the electrode-electrolyte interface. The frequency and voltage windows observed in previous tetrapolar analysis were repeated in the tripolar

  9. Electrohydrodynamics of suspension of liquid drops in AC fields

    Science.gov (United States)

    Abdul Halim, Md.; Esmaeeli, Asghar

    2012-11-01

    Manipulation of liquid drops by an externally applied electric field is currently the focus of increased attention because of its relevance in a broad range of industrial processes. The effect of a uniform DC electric field on a solitary drop is well studied; however, less is know about the impact of electric field on suspension of liquid drops, and very little information is available on the impact of AC field on a single or a suspension of drops. Here we report the results of Direct Numerical Simulations of electrohydrodynamics of suspension of liquid drops. The governing equations are solved using a front tracking/finite difference technique, in conjunction with Taylor's leaky dielectric model. The imposed electric potential comprises of two parts, a time-independent base and a time-dependent part. The goal is to explore the relative importance of these two components in setting the statistically steady state behavior of the suspension. To this end, we report the results of three sets of simulations, where (i) the time-dependent part act as a perturbation on the base potential, (ii) the two components are of the same order, and (iii) the time-dependent part is much larger than the base potential. The problem is studied as a function of the governing nondimensional parameters.

  10. Numerical study of inertial effects on the rheology of filament suspensions

    Science.gov (United States)

    Alizad Banaei, Arash; Rosti, Marco Edoardo; Brandt, Luca

    2017-11-01

    Significant work has been devoted to modeling fiber suspensions as they occur in many applications such as paper and food industries. Most of the works are limited to the motion of rigid cylindrical rods in low Stokes flows. Here, we investigate the rheological properties of flexible filament suspensions by means of numerical simulations. We considered the filaments as one-dimensional inextensible slender bodies obeying the Euler-Bernoulli equations and study the effect of flexibility, flow inertia and volume fraction on the rheology of the suspensions. The numerical simulations are performed using the Immersed Boundary Method to model the fluid/structure interaction. The results indicate that the inertia has significant effect on the relative viscosity of the suspensions. The effect is larger for less deformable filaments. The filament suspensions exhibit viscoelastic behavior and the first normal stress has a maximum for moderate flexibilities. The relative viscosity increases with volume fraction of the filaments and it is more sensitive to the volume fraction for larger Reynolds numbers. For a constant flexibility, the mean end-to-end distance of the filaments decreases with Reynolds number and the mean velocity fluctuations of the fluid increases with the Reynolds number. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

  11. Computation of magnetic suspension of maglev systems using dynamic circuit theory

    Science.gov (United States)

    He, J. L.; Rote, D. M.; Coffey, H. T.

    1992-01-01

    Dynamic circuit theory is applied to several magnetic suspensions associated with maglev systems. These suspension systems are the loop-shaped coil guideway, the figure-eight-shaped null-flux coil guideway, and the continuous sheet guideway. Mathematical models, which can be used for the development of computer codes, are provided for each of these suspension systems. The differences and similarities of the models in using dynamic circuit theory are discussed in the paper. The paper emphasizes the transient and dynamic analysis and computer simulation of maglev systems. In general, the method discussed here can be applied to many electrodynamic suspension system design concepts. It is also suited for the computation of the performance of maglev propulsion systems. Numerical examples are presented in the paper.

  12. Applied research on energy storage and conversion for photovoltaic and wind energy systems. Volume II. Photovoltaic systems with energy storage. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    This volume of the General Electric study was directed at an evaluation of those energy storage technologies deemed best suited for use in conjunction with a photovoltaic energy conversion system in utility, residential and intermediate applications. Break-even cost goals are developed for several storage technologies in each application. These break-even costs are then compared with cost projections presented in Volume I of this report to show technologies and time frames of potential economic viability. The form of the presentation allows the reader to use more accurate storage system cost data as they become available. The report summarizes the investigations performed and presents the results, conclusions and recommendations pertaining to use of energy storage with photovoltaic energy conversion systems. Candidate storage concepts studied include (1) above ground and underground pumped hydro, (2) underground compressed air, (3) electric batteries, (4) flywheels, and (5) hydrogen production and storage. (WHK)

  13. Attractive and repulsive magnetic suspension systems overview

    Science.gov (United States)

    Cope, David B.; Fontana, Richard R.

    1992-01-01

    Magnetic suspension systems can be used in a wide variety of applications. The decision of whether to use an attractive or repulsive suspension system for a particular application is a fundamental one which must be made during the design process. As an aid to the designer, we compare and contrast attractive and repulsive magnetic suspension systems and indicate whether and under what conditions one or the other system is preferred.

  14. Introducing Dual Suspension System in Road Vehicles

    OpenAIRE

    Imtiaz Hussain; Jawaid Daudpoto; Ali Asghar Memon

    2013-01-01

    The main objective of suspension system is to reduce the motions of the vehicle body with respect to road disturbances. The conventional suspension systems in road vehicles use passive elements such as springs and dampers to suppress the vibrations induced by the irregularities in the road. But these conventional suspension systems can suppress vibrations to a certain limit. This paper presents a novel idea to improve the ride quality of roads vehicles without compromising vehicle?s stability...

  15. Simulation of elution profiles in liquid chromatography - II: Investigation of injection volume overload under gradient elution conditions applied to second dimension separations in two-dimensional liquid chromatography.

    Science.gov (United States)

    Stoll, Dwight R; Sajulga, Ray W; Voigt, Bryan N; Larson, Eli J; Jeong, Lena N; Rutan, Sarah C

    2017-11-10

    An important research direction in the continued development of two-dimensional liquid chromatography (2D-LC) is to improve the detection sensitivity of the method. This is especially important in applications where injection of large volumes of effluent from the first dimension ( 1 D) column into the second dimension ( 2 D) column leads to severe 2 D peak broadening and peak shape distortion. For example, this is common when coupling two reversed-phase columns and the organic solvent content of the 1 D mobile phase overwhelms the 2 D column with each injection of 1 D effluent, leading to low resolution in the second dimension. In a previous study we validated a simulation approach based on the Craig distribution model and adapted from the work of Czok and Guiochon [1] that enabled accurate simulation of simple isocratic and gradient separations with very small injection volumes, and isocratic separations with mismatched injection and mobile phase solvents [2]. In the present study we have extended this simulation approach to simulate separations relevant to 2D-LC. Specifically, we have focused on simulating 2 D separations where gradient elution conditions are used, there is mismatch between the sample solvent and the starting point in the gradient elution program, injection volumes approach or even exceed the dead volume of the 2 D column, and the extent of sample loop filling is varied. To validate this simulation we have compared results from simulations and experiments for 101 different conditions, including variation in injection volume (0.4-80μL), loop filling level (25-100%), and degree of mismatch between sample organic solvent and the starting point in the gradient elution program (-20 to +20% ACN). We find that that the simulation is accurate enough (median errors in retention time and peak width of -1.0 and -4.9%, without corrections for extra-column dispersion) to be useful in guiding optimization of 2D-LC separations. However, this requires that real

  16. Time Varying Behavior of the Loudspeaker Suspension

    DEFF Research Database (Denmark)

    Pedersen, Bo Rohde; Agerkvist, Finn T.

    2007-01-01

    The suspension part of the electrodynamic loudspeaker is often modelled as a simple linear spring with viscous damping, however the dynamic behaviour of the suspension is much more complicated than predicted by such a simple model. At higher levels the compliance becomes non-linear and often chan...... changes during excitation at high levels. This paper investigates how the compliance of the suspension depends on the excitation, i.e. level and frequency content. The measurements are compared with other known measurement methods of the suspension....

  17. Introducing Dual Suspension System in Road Vehicles

    Directory of Open Access Journals (Sweden)

    Imtiaz Hussain

    2013-04-01

    Full Text Available The main objective of suspension system is to reduce the motions of the vehicle body with respect to road disturbances. The conventional suspension systems in road vehicles use passive elements such as springs and dampers to suppress the vibrations induced by the irregularities in the road. But these conventional suspension systems can suppress vibrations to a certain limit. This paper presents a novel idea to improve the ride quality of roads vehicles without compromising vehicle?s stability. The paper proposes the use of primary and secondary suspension to suppress the vibrations more effectively.

  18. Settling of isolated particles and of suspensions in a shear-thinning medium; Sedimentation de particules isolees et de suspensions en milieu rheofluidifiant

    Energy Technology Data Exchange (ETDEWEB)

    Daugan, S.

    2002-11-01

    After drawing up a balance sheet of current knowledge of settling of particles and suspensions in Newtonian and non Newtonian fluids, we introduce the characterisation of the fluid-particles system and especially the shear-thinning behavior of Xanthan solutions. This experimental study is organised into two parts. First of all, we study the settling behavior of a few particles falling along their line of centres. The conditions for particles aggregation with respect to the rheological properties of the suspending fluid are systematically reported. To that extent, rheological relaxation experiments are performed. Once aggregated, the particles velocities are much more important that the velocity of a single one. We show that a simple model, based on the Newtonian case, allows to predict the position and the velocity of each particle with respect to the initial separation distance between them. The second part of this work is devoted to the study of the settling behavior of spherical and monodisperse particles suspensions according to the particles volume fraction, the polymer concentration of the suspending fluid and the geometry of the sedimenting cell. From a model giving the particle volume fraction as a function of the luminous intensity transmitted by the suspension, we show that three regimes of different kinetics occur. During the second regime, the particle volume fraction decreases exponentially with time and the observed phenomena are very fast. Finally, we study the spatial structuration of the suspension and we link it to the topography of the sediment obtained at the end of the sedimentation. (author)

  19. Revisiting homogeneous suspension reactors for production of radioisotopes

    International Nuclear Information System (INIS)

    Pasqualini, E.E.

    2010-01-01

    Some 50 years ago in Geneva Conferences I, II and III (1955. 1958 and 1964) on the Peaceful Uses of Atomic Energy, and also in Vienna Symposium on Reactor Experiments (1961), several papers where presented by different countries referring to advances in homogeneous suspension reactors. In particular the Dutch KEMA Suspension Test Reactor (KSTR) was developed, built and successfully operated in the sixties and seventies. It was a 1MWth reactor in which a suspension (6 microns spheres) of mixed UO 2 /ThO 2 in light water was circulated in a closed loop through a sphere-shaped vessel. One of the basic ideas on these suspension reactors was to apply the fission recoil separation effect as a means of purification of the fuel: the non-volatile fission products can be adsorbed in dispersed active charcoal and removed from the liquid. Undoubtedly, this method can present some advantages and better yields for the production of Mo-99 and other short lived radioisotopes, since they have to be extracted from a liquid in which practically no uranium is present. Details are mentioned of the different aspects that have been taken into account and which ones could be added in the corresponding actualization of suspension reactors for radioisotope production. In recent years great advances have been made in nanotechnology that can be used in the tailoring of fuel particles and adsorbent media. Recently, in CNEA Buenos Aires, a new facility has been inaugurated and is being equipped and licensed for laboratory experiments and preparative synthesis of nuclear nanoparticles. RA-6 and RA-3 experimental reactors in Argentina can be used for in-pile testing. (author)

  20. Sedimentation of athermal particles in clay suspensions

    Science.gov (United States)

    Clotet, Xavier; Kudrolli, Arshad

    2015-03-01

    We discuss sedimentation of athermal particles in dense clay suspensions which appear liquid-like to glass-like. These studies are motivated by the physics important to a diverse range of problems including remediation of oil sands after the extraction of hydrocarbons, and formation of filter cakes in bore wells. We approach this problem by first considering collective sedimentation of athermal spherical particles in a viscous liquid in quasi-two dimensional and three dimensional containers. We examine the system using optical and x-ray tomography techniques which gives particle level information besides global information on the evolution of the volume fraction. Unlike sediments in the dilute limit - which can be modeled as isolated particles that sediment with a constant velocity and slow down exponentially as they approach the bottom of the container - we find interaction between the particles through the viscous fluids leads to qualitatively differences. We find significant avalanching behavior and cooperative motion as the grains collectively settle, and non-exponential increase in settling time. We discuss the effect of stirring caused by the sedimenting particles on their viscosity and consequently the sedimentation rates as a function of particle concentration. Supported by Petroleum Research Fund Grant PRF # 54045-ND9.

  1. Liquid crystalline phases in suspensions of pigments in non-polar solvents

    Science.gov (United States)

    Klein, Susanne; Richardson, Robert M.; Eremin, Alexey

    We will discuss colloid suspensions of pigments and compare their electro-optic properties with those of traditional dyed low molecular weight liquid crystal systems. There are several potential advantages of colloidal suspensions over low molecular weight liquid crystal systems: a very high contrast because of the high orientational order parameter of suspensions of rod shaped nano-particles, the excellent light fastness of pigments as compared to dyes and high colour saturations resulting from the high loading of the colour stuff. Although a weak `single-particle' electro-optic response can be observed in dilute suspensions, the response is very much enhanced when the concentration of the particles is sufficient to lead to a nematic phase. Excellent stability of suspensions is beneficial for experimental observation and reproducibility, but it is a fundamental necessity for display applications. We therefore discuss a method to achieve long term stability of dispersed pigments and the reasons for its success. Small angle X-ray scattering was used to determine the orientational order parameter of the suspensions as a function of concentration and the dynamic response to an applied electric field. Optical properties were investigated for a wide range of pigment concentrations. Electro-optical phenomena, such as field-induced birefringence and switching, were characterised. In addition, mixtures of pigment suspensions with small amounts of ferrofluids show promise as future magneto-optical materials.

  2. Experimental data and theoretical predictions for the rate of electrophoretic clarification of colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T.J.; Davis, E.J.

    2000-05-01

    An experimental and theoretical investigation of the electrophoretic clarification rate of colloidal suspensions was conducted. The suspensions included a coal-washing effluent and a model system of TiO{sub 2} particles. A parametric study of TiO{sub 2} suspensions was performed to validate and analysis of the electrophoretic motion of the clarification front formed between a clear zone and the suspension. To measure the electric field strength needed in the prediction of the location of the front, a moveable probe and salt bridge were connected to a reference electrode. Using the measured electric field strengths, it was found that the numerical solution to the unit cell electrophoresis model agrees with the measured clarification rates. For suspensions with moderately thick electric double layers and high particle volume fractions the deviations from classical Smoluchowski theory are substantial, and the numerical analysis is in somewhat better agreement with the data than a prior solution of the problem. The numerical model reduces to the predictions of previous theories as the thickness of the electric double layer decreases, and it is in good agreement with the clarification rate measured for a coal-washing effluent suspension with thin electric double layers.

  3. Experimental data and theoretical predictions of the rate of electrophoretic clarification of colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T.J.; Davis, E.J. [University of Washington, Seattle, WA (USA). Dept. of Chemical Engineering

    2000-05-01

    An experimental and theoretical investigation of the electrophoretic clarification rate of colloidal suspensions was conducted. The suspensions included a coal-washing effluent and a model system of TiO{sub 2} particles. A parametric study of TiO{sub 2} suspensions was performed to validate an analysis of the electrophoretic motion of the clarification front formed between a clear zone and the suspension. To measure the electric field strength needed in the prediction of the location of the front, a moveable probe and salt bridge were connected to a reference electrode. Using the measured electric field strength, it was found that the numerical solution to the unit cell electrophoresis model agrees with the measured clarification rates. For suspensions with moderately thick electric double layers and high particle volume fractions the deviations from classical Smoluchowski theory are substantial, and the numerical analysis is in somewhat better agreement with the data than a prior solution of the problem. The numerical model reduces to the predictions of previous theories as the thickness of the electric double layer decreases, and it is in good agreement with the clarification rate measured for a coal-washing effluent suspension with thin electric double layers. 21 refs., 8 figs., 4 tabs.

  4. Bulk and interfacial stresses in suspensions of soft and hard colloids

    International Nuclear Information System (INIS)

    Truzzolillo, D; Roger, V; Dupas, C; Cipelletti, L; Mora, S

    2015-01-01

    We explore the influence of particle softness and internal structure on both the bulk and interfacial rheological properties of colloidal suspensions. We probe bulk stresses by conventional rheology, by measuring the flow curves, shear stress versus strain rate, for suspensions of soft, deformable microgel particles and suspensions of near hard-sphere-like silica particles. A similar behaviour is seen for both kinds of particles in suspensions at concentrations up to the random close packing volume fraction, in agreement with recent theoretical predictions for sub-micron colloids. Transient interfacial stresses are measured by analyzing the patterns formed by the interface between the suspensions and their solvent, due to a generalized Saffman–Taylor hydrodynamic instability. At odds with the bulk behaviour, we find that microgels and hard particle suspensions exhibit vastly different interfacial stress properties. We propose that this surprising behaviour results mainly from the difference in particle internal structure (polymeric network for microgels versus compact solid for the silica particles), rather than softness alone. (paper)

  5. Applied geodesy

    International Nuclear Information System (INIS)

    Turner, S.

    1987-01-01

    This volume is based on the proceedings of the CERN Accelerator School's course on Applied Geodesy for Particle Accelerators held in April 1986. The purpose was to record and disseminate the knowledge gained in recent years on the geodesy of accelerators and other large systems. The latest methods for positioning equipment to sub-millimetric accuracy in deep underground tunnels several tens of kilometers long are described, as well as such sophisticated techniques as the Navstar Global Positioning System and the Terrameter. Automation of better known instruments such as the gyroscope and Distinvar is also treated along with the highly evolved treatment of components in a modern accelerator. Use of the methods described can be of great benefit in many areas of research and industrial geodesy such as surveying, nautical and aeronautical engineering, astronomical radio-interferometry, metrology of large components, deformation studies, etc

  6. Pipette tip with integrated electrodes for gene electrotransfer of cells in suspension: a feasibility study in CHO cells

    International Nuclear Information System (INIS)

    Rebersek, Matej; Kanduser, Masa; Miklavcic, Damijan

    2011-01-01

    Gene electrotransfer is a non-viral gene delivery method that requires successful electroporation for DNA delivery into the cells. Changing the direction of the electric field during the pulse application improves the efficacy of gene delivery. In our study, we tested a pipette tip with integrated electrodes that enables changing the direction of the electric field for electroporation of cell suspension for gene electrotransfer. A new pipette tip consists of four cylindrical rod electrodes that allow the application of electric pulses in different electric field directions. The experiments were performed on cell suspension of CHO cells in phosphate buffer. Plasmid DNA encoding for green fluorescent protein (GFP) was used and the efficiency of gene electrotransfer was determined by counting cells expressing GFP 24 h after the experiment. Experimental results showed that the percentage of cells expressing GFP increased when the electric field orientation was changed during the application. The GFP expression was almost two times higher when the pulses were applied in orthogonal directions in comparison with single direction, while cell viability was not significantly affected. We can conclude that results obtained with the described pipette tip are comparable to previously published results on gene electrotransfer using similar electrode geometry and electric pulse parameters. The tested pipette tip, however, allows work with small volumes/samples and requires less cell manipulation

  7. Rheo-SAXS investigation of shear-thinning behaviour of very anisometric repulsive disc-like clay suspensions.

    Science.gov (United States)

    Philippe, A M; Baravian, C; Imperor-Clerc, M; De Silva, J; Paineau, E; Bihannic, I; Davidson, P; Meneau, F; Levitz, P; Michot, L J

    2011-05-18

    Aqueous suspensions of swelling clay minerals exhibit a rich and complex rheological behaviour. In particular, these repulsive systems display strong shear-thinning at very low volume fractions in both the isotropic and gel states. In this paper, we investigate the evolution with shear of the orientational distribution of aqueous clay suspensions by synchrotron-based rheo-SAXS experiments using a Couette device. Measurements in radial and tangential configurations were carried out for two swelling clay minerals of similar morphology and size, Wyoming montmorillonite and Idaho beidellite. The shear evolution of the small angle x-ray scattering (SAXS) patterns displays significantly different features for these two minerals. The detailed analysis of the angular dependence of the SAXS patterns in both directions provides the average Euler angles of the statistical effective particle in the shear plane. We show that for both samples, the average orientation is fully controlled by the local shear stress around the particle. We then apply an effective approach to take into account multiple hydrodynamic interactions in the system. Using such an approach, it is possible to calculate the evolution of viscosity as a function of shear rate from the knowledge of the average orientation of the particles. The viscosity thus recalculated almost perfectly matches the measured values as long as collective effects are not too important in the system.

  8. Rheo-SAXS investigation of shear-thinning behaviour of very anisometric repulsive disc-like clay suspensions

    International Nuclear Information System (INIS)

    Philippe, A M; Baravian, C; Imperor-Clerc, M; De Silva, J; Davidson, P; Paineau, E; Bihannic, I; Michot, L J; Meneau, F; Levitz, P

    2011-01-01

    Aqueous suspensions of swelling clay minerals exhibit a rich and complex rheological behaviour. In particular, these repulsive systems display strong shear-thinning at very low volume fractions in both the isotropic and gel states. In this paper, we investigate the evolution with shear of the orientational distribution of aqueous clay suspensions by synchrotron-based rheo-SAXS experiments using a Couette device. Measurements in radial and tangential configurations were carried out for two swelling clay minerals of similar morphology and size, Wyoming montmorillonite and Idaho beidellite. The shear evolution of the small angle x-ray scattering (SAXS) patterns displays significantly different features for these two minerals. The detailed analysis of the angular dependence of the SAXS patterns in both directions provides the average Euler angles of the statistical effective particle in the shear plane. We show that for both samples, the average orientation is fully controlled by the local shear stress around the particle. We then apply an effective approach to take into account multiple hydrodynamic interactions in the system. Using such an approach, it is possible to calculate the evolution of viscosity as a function of shear rate from the knowledge of the average orientation of the particles. The viscosity thus recalculated almost perfectly matches the measured values as long as collective effects are not too important in the system.

  9. 36 CFR 296.10 - Suspension and revocation of permits.

    Science.gov (United States)

    2010-07-01

    ... AGRICULTURE PROTECTION OF ARCHAEOLOGICAL RESOURCES: UNIFORM REGULATIONS § 296.10 Suspension and revocation of... correct the situation which led to suspension of the permit. (b) Suspension or revocation for management...

  10. Design analysis of formula student race car suspension system

    Science.gov (United States)

    Wirawan, Julian Wisnu; Ubaidillah, Aditra, Rama; Alnursyah, Rafli; Rahman, Rizki Abdul; Cahyono, Sukmaji Indro

    2018-02-01

    Design analysis of suspension especially for racecar suspension is very crucial to achieve maximum performance and handling. Suspension design may vary depending on the road terrain and the vehicle purpose itself, such as high speed or off-road vehicle. This paper focused on the suspension which used for racecar vehicle. The suspension type used was unequal double wishbone. This model is used because of its stability for high-speed usage compared to another kind of suspension. The suspension parameter was calculated to achieve desired performance. The result is the motion ratio of the designed suspension geometry. The obtained value of motion ratio was 1:2 for front suspension and 1:1 for the rear suspension. These calculation result the front suspension is still too soft, which the optimal motion ratio should be kept around 1:1 for better handling. This problem caused by the lack of space for suspension linkage.

  11. 49 CFR 393.207 - Suspension systems.

    Science.gov (United States)

    2010-10-01

    ... braking system. The vehicle shall be level (not tilting to the left or right). Air leakage shall not be... 49 Transportation 5 2010-10-01 2010-10-01 false Suspension systems. 393.207 Section 393.207... NECESSARY FOR SAFE OPERATION Frames, Cab and Body Components, Wheels, Steering, and Suspension Systems § 393...

  12. 41 CFR 105-74.670 - Suspension.

    Science.gov (United States)

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false Suspension. 105-74.670 Section 105-74.670 Public Contracts and Property Management Federal Property Management Regulations System...-GOVERNMENTWIDE REQUIREMENTS FOR DRUG-FREE WORKPLACE (FINANCIAL ASSISTANCE) Definitions § 105-74.670 Suspension...

  13. 36 CFR 25.3 - Supervision; suspensions.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Supervision; suspensions. 25.3 Section 25.3 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR NATIONAL MILITARY PARKS; LICENSED GUIDE SERVICE REGULATIONS § 25.3 Supervision; suspensions. (a) The guide service will operate under the direction...

  14. Stability of an extemporaneously prepared alcohol-free phenobarbital suspension.

    Science.gov (United States)

    Cober, Mary Petrea; Johnson, Cary E

    2007-03-15

    The physical and chemical short-term stability of alcohol-free, oral suspensions of phenobarbital 10 mg/mL prepared from commercially available tablets in both a sugar and a sugar-free vehicle was assessed at room temperature. Phenobarbital oral suspension 10 mg/mL was prepared by crushing 10 60-mg tablets of phenobarbital with a mortar and pestle. A small amount of Ora-Plus was added to the phenobarbital powder to sufficiently wet the particles. A 1:1 mixture of Ora-Plus and either Ora-Sweet or Ora-Sweet SF was combined with the phenobarbital powder to produce a final volume of 60 mL. Three identical samples of each of the two different formulations were prepared and stored at room temperature in 2-oz amber plastic bottles. Immediately after preparation and at 15, 30, 60, and 115 days, the samples were assayed in duplicate by stability-indicating high-performance liquid chromatography. The samples were tasted and inspected for color and odor changes. The percent of the initial concentration remaining at each study time for each phenobarbital suspension was determined. Stability was defined as the retention of at least 90% of the initial concentration. There were no detectable changes in color, odor, and taste and no visible microbial growth in any sample. At least 98% of the initial phenobarbital concentration remained throughout the 115-day study period in both preparations. An extemporaneously prepared alcohol-free suspension of phenobarbital 10 mg/mL in a 1:1 mixture of Ora-Plus and Ora-Sweet or Ora-Sweet SF was stable for at least 115 days when stored in 2-oz amber plastic bottles at room temperature.

  15. Applied research on energy storage and conversion for photovoltaic and wind energy systems. Volume I. Study summary and concept screening. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1978-01-01

    This study was directed at a review of storage technologies, and particularly those which might be best suited for use in conjunction with wind and photovoltaics. The potential ''worth'' added by incorporating storage was extensively analyzed for both wind and photovoltaics. Energy storage concepts studied include (1) above ground pumped hydro storage, (2) underground pumped hydro storage, (3) thermal storage-oil, (4) thermal storage-steam, (5) underground compressed air storage, (6) pneumatic storage, (7) lead-acid batteries, (8) advanced batteries, (9) inertial storage (flywheel), (10) hydrogen generation and storage, and (11) superconducting magnetic energy storage. The investigations performed and the major results, conclusions, and recommendations are presented in this volume. (WHK)

  16. Suspension chemistry and electrophoretic deposition of zirconia electrolyte on conducting and non-conducting substrates

    International Nuclear Information System (INIS)

    Das, Debasish; Basu, Rajendra N.

    2013-01-01

    Graphical abstract: - Highlights: • Stable suspension of yttria stabilized zirconia (YSZ) obtained in isopropanol medium. • Suspension chemistry and process parameters for electrophoretic deposition optimized. • Deposited film quality changed with iodine and water (dispersants) concentration. • Dense YSZ film (∼5 μm) fabricated onto non-conducting porous NiO-YSZ anode substrate. - Abstract: Suspensions of 8 mol% yttria stabilized zirconia (YSZ) particulates in isopropanol medium are prepared using acetylacetone, iodine and water as dispersants. The effect of dispersants concentration on suspension stability, particle size distribution, electrical conductivity and pH of the suspensions are studied in detail to optimize the suspension chemistry. Electrophoretic deposition (EPD) has been conducted to produce thin and dense YSZ electrolyte films. Deposition kinetics have been studied in depth and good quality films on conducting substrate are obtained at an applied voltage of 15 V for 3 min. YSZ films are also fabricated on non-conducting NiO-YSZ anode substrate using a steel plate on the reverse side of the substrate. Upon co-firing at 1400 °C for 6 h a dense YSZ film of thickness ∼5 μm is obtained. Such a half cell (anode + electrolyte) can be used to fabricate a solid oxide fuel cell on applying a suitable cathode layer

  17. Lateral Vibration Attenuation by the Dynamic Adjustment of Bias Currents in Magnetic Suspension System

    International Nuclear Information System (INIS)

    Mizuno, Takeshi; Takasaki, Masaya; Ishino, Yuji

    2016-01-01

    Switching stiffness control is applied to attenuate vibration in the lateral directions in an active magnetic suspension system with electromagnets operated in differential mode. The magnetic suspension system using the attractive force between magnetized bodies is inherently unstable in the normal direction so that feedback control is necessary to achieve stable suspension. In contrast, it can be stable in the lateral directions due to the edge effects in the magnetic circuits. In several applications, such passive suspension is used in combination with the active one to reduce cost and space. However, damping in the lateral directions is generally small. As a result, induced vibrations in these directions are hardly attenuated. To suppress such vibration without any additional actuator (electromagnet), switching stiffness control is applied to an magnetic suspension system operated in the differential mode. The stiffness in the lateral direction is adjusted by varying the bias currents of an opposed pair of electromagnets located in the normal direction simultaneously according to the motion of the suspended object. When the varied bias currents are adjusted for the additive normal forces cancel each other, such control does not affect the suspension in the normal direction. The effectiveness of the proposed control methods is confirmed experimentally. (paper)

  18. Next Generation Suspension Dynamics Algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, Peter Randall [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Higdon, Jonathon [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Chen, Steven [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2014-12-01

    This research project has the objective to extend the range of application, improve the efficiency and conduct simulations with the Fast Lubrication Dynamics (FLD) algorithm for concentrated particle suspensions in a Newtonian fluid solvent. The research involves a combination of mathematical development, new computational algorithms, and application to processing flows of relevance in materials processing. The mathematical developments clarify the underlying theory, facilitate verification against classic monographs in the field and provide the framework for a novel parallel implementation optimized for an OpenMP shared memory environment. The project considered application to consolidation flows of major interest in high throughput materials processing and identified hitherto unforeseen challenges in the use of FLD in these applications. Extensions to the algorithm have been developed to improve its accuracy in these applications.

  19. Graphite suspension in carbon dioxide

    International Nuclear Information System (INIS)

    Roche, R.

    1965-01-01

    Since 1963 the Atomic Division of SNECMA has been conducting, under a contract with the CEA, an experimental work with a two-component fluid comprised of carbon dioxide and small graphite particles. The primary purpose was the determination of basic engineering information pertaining to the stability and the flowability of the suspension. The final form of the experimental loop consists mainly of the following items: a light-phase compressor, a heavy-phase pump, an electrical-resistance type heater section, a cooling heat exchanger, a hairpin loop, a transparent test section and a separator. During the course of the testing, it was observed that the fluid could be circulated quite easily in a broad range of variation of the suspension density and velocity - density from 30 to 170 kg/m 3 and velocity from 2 to 24 m/s. The system could be restarted and circulation maintained without any difficulty, even with the heavy-phase pump alone. The graphite did not have a tendency to pack or agglomerate during operation. No graphite deposition was observed on the wall of the tubing. A long period run (250 hours) has shown the evolution of the particle dimensions. Starting with graphite of surface area around 20 m 2 /g (graphite particles about 1 μ), the powder surface area reaches an asymptotic value of 300 m 2 /g (all the particles less than 0.3 μ). Moisture effect on flow stability, flow distribution between two parallel channels, pressure drop in straight tubes, recompression ratio in diffusers were also investigated. (author) [fr

  20. Brownian dynamics simulations of an order-disorder transition in sheared sterically stabilized colloidal suspensions

    International Nuclear Information System (INIS)

    Rigos, A.A.; Wilemski, G.

    1992-01-01

    The shear thinning behavior of a sterically stabilized nonaqueous colloidal suspension was investigated using nonequilibrium Brownian dynamics simulations of systems with 108 and 256 particles. At a volume fraction of 0.4, the suspension is thixotropic: it has a reversible shear thinning transition from a disordered state to an ordered, lamellar state with triangularly packed strings of particles. The time scale for the transition is set by the free particle diffusion constant. For the smaller system, the transition occurs gradually with increasing shear rate. For the larger system, the transition is sharp and discontinuous shear thinning is found. 34 refs., 9 figs., 1 tab

  1. Characterization of cell suspensions from solid tumors

    International Nuclear Information System (INIS)

    Pallavicini, M.

    1985-01-01

    The desirable features of cells in suspension will necessarily be dependent upon the use for which the cells were prepared. Adequate cell yield or recovery is defined by the measurement to be performed. Retention of cellular morphology is important for microscopic identification of cell types in a heterogenous cell suspension, and may be used to determine whether the cells in suspension are representative of those in the tumor in situ. Different dispersal protocols may yield cells with different degrees of clonogenicity, as well as altered biochemical features, such as loss of cellular proteins, surface antigens, nucleotide pools, etc. The quality of the cell suspension can be judged by the degree of cell clumping and level of cellular debris, both of which impact on flow cytometric measurements and studies in which the number of cells be known accurately. Finally, if the data measured on the cells in suspension are to be extrapolated to phenomena occurring in the tumor in situ, it is desirable that the cells in suspension are representative of those in the solid tumor in vivo. This report compares characteristics of tumor cell suspensions obtained by different types of selected disaggregation methods. 33 refs., 2 figs., 4 tabs

  2. Stereotaxic implantation of dispersed cell suspensions into brain. A systematic appraisal of cell placement and survival

    International Nuclear Information System (INIS)

    Plunkett, R.J.; Weber, R.J.; Oldfield, E.H.

    1988-01-01

    The application of several recent advances in cell biology, brain implantation, and cell-mediated tumor immunotherapy requires successful and reproducible placement of viable cell suspensions into brain. Stereotaxic implantation is being used to inject cytotoxic lymphocytes into gliomas and to replace dopaminergic cells in parkinsonian models. Systematic assessment of the factors that influence success in implantation of cell suspensions into solid tissues is needed. A model was developed for investigation of stereotaxic implantation using radiolabeled rat lymphokine-activated killer (LAK) cells. Anesthetized rats received microliter injections of cell suspension into the right caudate nucleus. The injection volume, cell concentration, infusion rate, and needle size were varied systematically. The animals were sacrificed 1 hour after injection; the brain was removed and sectioned, and the radioactivity was counted. Three aliquots of the suspension were injected into counting tubes for control analysis. Recovery of radioactivity was expressed as the percent of mean counts per minute (cpm) in the right frontal lobe/mean cpm in the three control tubes. To assess the viability of implanted cells, the right frontal region was mechanically dissociated in media and centrifuged, and the pellet and supernatant were counted. By using small needles and slow infusion of volumes of 10 microliters or less, 85% to 90% of the radioactivity was recovered in the caudate nucleus. At least half of the implanted cells were viable. Consistent, accurate implantation of dispersed cells into brain over a range of volumes, cell concentrations, infusion rates, and needle sizes was achieved

  3. Survey of potential applications of superconducting suspensions

    International Nuclear Information System (INIS)

    Rao, D.K.; Bupara, S.S.

    1993-01-01

    The purpose of this report is to survey the recent developments in applying the bulk superconductors to mechanical applications. These applications, called superconducting suspensions, can be broadly divided into three groups - Passive Magnetic Bearings, Passive Superconducting Dampers and Active Superconducting Bearings. Basically, passive magnetic bearings utilize bulk superconductors to support a rotating shaft without contact while active superconducting bearings employ superconducting wires. Passive superconducting dampers, on the other hand, dissipate energy from a vibrating component. Over the past one year, dramatic improvements have been made in processing large-size specimens made of high grade bulk superconductors. As a result, they can meet the size requirements and load capacity requirements of many applications. With this size-scale up, one can utilize them in a wider number of applications than what was possible a few years back. At present several organizations have demonstrated the capability of passive magnetic bearings. The targeted applications include miniature cryoturboexpanders, cryoturbopumps, energy storage wheels and turbomolecular pumps. These demonstrations indicate that the passive magnetic bearings are closer to technology maturity. (orig.)

  4. Magnetic suspension characteristics of electromagnetic actuators

    Science.gov (United States)

    Rao, Dantam K.; Dill, J.; Zorzi, E.

    1993-01-01

    Electromagnetic actuators that use a current-carrying coil (which is placed in a magnetic field) to generate mechanical force are conceptually attractive components for active control of rotating shafts. In one concept that is being tested in the laboratory, the control forces from such actuators are applied on the flexibly supported bearing housings of the rotor. Development of this concept into a practical reality requires a clear and thorough understanding of the role of electromechanical parameters of these actuators in delivering the right amount of control force at the right phase into the rotor. The electromechanical parameters of the actuators investigated are the mass of the armature, stiffness of its suspension, electrical resistance, and inductance of the coils. Improper selection of these parameters can result in degradation in their performance, leading to mistuning between the actuator and the rotor. Through a simple analysis, it is shown that use of such mistuned actuators could result in sharp fluctuations in the phase of the control force delivered into the rotor around the critical speeds. These sharp fluctuations in phase, called 'Phase Glitches', are undesirable. Hence, future designs of controllers should take into account the undesirable mistuning effects between the actuator and the rotor caused by the phase glitches.

  5. Vehicle lateral dynamics stabilization using active suspension

    Directory of Open Access Journals (Sweden)

    Drobný V.

    2008-12-01

    Full Text Available The paper deals with the investigation of active nonlinear suspension control in order to stabilize the lateral vehicle motion in similar way as systems like ESP do. The lateral stabilization of vehicle based on braking forces can be alternatively provided by the different setting of suspension forces. The basis of this control is the nonlinear property of the tyres. The vehicle has at least four wheels and it gives one or more redundant vertical forces that can be used for the different distribution of vertical suspension forces in such a way that resulting lateral and/or longitudinal forces create the required correction moment for lateral dynamic vehicle stabilization.

  6. Suspension for the low frequency facility

    CERN Document Server

    Cella, G; Di Virgilio, A; Gaddi, A; Viceré, A

    2000-01-01

    We introduce the working principles of the VIRGO Low Frequency Facility (LFF), whose main aim is the measurement of the thermal noise in the VIRGO suspension system. We evaluate the displacement thermal noise of a mirror, which is an intermediate element of a double pendulum suspension system. This double pendulum will be suspended to the last stage of a VIRGO Super-Attenuator (SA), the prototype VIRGO suspension system being tested at the Pisa section of INFN. In the proposed configuration, we evaluate the spectrum of the thermal noise for different choices of the parameters: based on this study, we comment on the future directions to be undertaken in the LFF experiment.

  7. A new method of simulating fiber suspensions and applications to channel Flows

    KAUST Repository

    Yang, Wei

    2012-06-01

    A successive iteration method is proposed to numerically simulate fiber suspensions. The computational field is discretized with the collocated finite volume method, and an ergodic hypothesis is adopted to greatly accelerate the solution to the Fokker - Planck equation. The method is employed in channel flows with different fiber volume fractions and aspect ratios, and its effectiveness is proved. The numerical results show that the existence of fibers significantly changes the pressure distribution, and the fiber aspect ratio has a greater effect on the velocity profile than on the volume faction. At the center of the channel, the velocity increases along the streamwise direction, while the velocity near the wall decreases slightly. The uncoupling and coupling solutions of the additional stress of the fiber suspensions are quite different. © 2012 Chinese Physical Society and IOP Publishing Ltd.

  8. A new method of simulating fiber suspensions and applications to channel Flows

    KAUST Repository

    Yang, Wei; Zhou, Kun

    2012-01-01

    A successive iteration method is proposed to numerically simulate fiber suspensions. The computational field is discretized with the collocated finite volume method, and an ergodic hypothesis is adopted to greatly accelerate the solution to the Fokker - Planck equation. The method is employed in channel flows with different fiber volume fractions and aspect ratios, and its effectiveness is proved. The numerical results show that the existence of fibers significantly changes the pressure distribution, and the fiber aspect ratio has a greater effect on the velocity profile than on the volume faction. At the center of the channel, the velocity increases along the streamwise direction, while the velocity near the wall decreases slightly. The uncoupling and coupling solutions of the additional stress of the fiber suspensions are quite different. © 2012 Chinese Physical Society and IOP Publishing Ltd.

  9. Stress hysteresis as the cause of persistent holes in particulate suspensions

    Science.gov (United States)

    Deegan, Robert D.

    2010-03-01

    Concentrated particulate suspensions under vibrations can support stable, localized, vertically oriented free surfaces. The most robust of these structures are persistent holes: deep and stable depressions of the interface. Using a reduced model of the hydrodynamics we show that a rheology with hysteresis can lead to motion opposite to the time-averaged applied force. Moreover, we show experimentally that particulate suspensions of cornstarch in water exhibits hysteresis in the shear-rate response to an applied sinusoidal stress. The results of our model and our experiments suggest that hysteresis accounts for the outward force needed to support persistent holes.

  10. Investigating high-concentration monoclonal antibody powder suspension in nonaqueous suspension vehicles for subcutaneous injection.

    Science.gov (United States)

    Bowen, Mayumi; Armstrong, Nick; Maa, Yuh-Fun

    2012-12-01

    Developing high-concentration monoclonal antibody (mAb) liquid formulations for subcutaneous (s.c.) administration is challenging because increased viscosity makes injection difficult. To overcome this obstacle, we investigated a nonaqueous powder suspension approach. Three IgG1 mAbs were spray dried and suspended at different concentrations in Miglyol® 840, benzyl benzoate, or ethyl lactate. Suspensions were characterized for viscosity, particle size, and syringeability; physical stability was visually inspected. Suspensions generally outperformed liquid solutions for injectability despite higher viscosity at the same mAb concentrations. Powder formulations and properties had little effect on viscosity or injectability. Ethyl lactate suspensions had lowest viscosity (Miglyol® 840 improved overall performance in high mAb concentration suspensions. This study demonstrated the viability of high mAb concentration (>300 mg/mL) in suspension formulations for s.c. administration. Copyright © 2012 Wiley Periodicals, Inc.

  11. Research of Biogas Purification Using Microalgae Monoraphidium Griffithii Suspension

    Directory of Open Access Journals (Sweden)

    Živilė Bingelytė

    2017-09-01

    Full Text Available Using biogas instead of fossil fuels decreases pollutants such as solid particles, sulphur dioxide, nitrogen oxides concentrations in the environment. Green energy and development of relevant infrastructure improves air quality considerably. Chemical, physical, biological methods are used for biogas purification. The main difficulties using biological methods are selection of suitable microorganisms’ suspensions and making optimal conditions in photobioreactor. Different origin and structure microalgae suspensions are used applying biological treatment methods. Monoraphidium griffithi, which is widespread in fresh water, has relatively high potential. Microalgae’ cultures absorb the main components of biogas – carbon dioxide (CO2 and hydrogen sulphide (H2S. Absorbtion processes are based on photosynthesis. Microalgae absorb specific components of biogas when there are suitable light source and nutrient solvent. The main purposes of the research are to asses emission of biogas using different substrates (chicken manure and wastewater sludge. Also, it was measured main physical and chemical characteristics of both substrates: acidicy, temperature, redox potential, conductivity, biohemical oxygen demand. According results of the research, emission from wastewater sludge is greater than from chicken manure so sludge was chosen in teh next stage of the research. The next stage – asssessment of purification efficienty using Monoraphidium grifftihii suspension. Raw biogas was supplied to photobioreacor (with microalgae suspension. Alterations of methane, carbon dioxide, oxygen, hydrogen sulphide concentrations were measured precisely. According to results concentration of methane in the beginning of the researc was 62%, after 35 days – 69%. Meanwhile carbon dioxide – 37% and 31% by analogy. Experimental research alows to assess Monoraphidium griffithi absorption capacity of ballast components. Results were compared to different scientists

  12. Multiobjective optimisation of bogie suspension to boost speed on curves

    Science.gov (United States)

    Milad Mousavi-Bideleh, Seyed; Berbyuk, Viktor

    2016-01-01

    To improve safety and maximum admissible speed on different operational scenarios, multiobjective optimisation of bogie suspension components of a one-car railway vehicle model is considered. The vehicle model has 50 degrees of freedom and is developed in multibody dynamics software SIMPACK. Track shift force, running stability, and risk of derailment are selected as safety objective functions. The improved maximum admissible speeds of the vehicle on curves are determined based on the track plane accelerations up to 1.5 m/s2. To attenuate the number of design parameters for optimisation and improve the computational efficiency, a global sensitivity analysis is accomplished using the multiplicative dimensional reduction method (M-DRM). A multistep optimisation routine based on genetic algorithm (GA) and MATLAB/SIMPACK co-simulation is executed at three levels. The bogie conventional secondary and primary suspension components are chosen as the design parameters in the first two steps, respectively. In the last step semi-active suspension is in focus. The input electrical current to magnetorheological yaw dampers is optimised to guarantee an appropriate safety level. Semi-active controllers are also applied and the respective effects on bogie dynamics are explored. The safety Pareto optimised results are compared with those associated with in-service values. The global sensitivity analysis and multistep approach significantly reduced the number of design parameters and improved the computational efficiency of the optimisation. Furthermore, using the optimised values of design parameters give the possibility to run the vehicle up to 13% faster on curves while a satisfactory safety level is guaranteed. The results obtained can be used in Pareto optimisation and active bogie suspension design problems.

  13. Ride performance of a high speed rail vehicle using controlled semi active suspension system

    Science.gov (United States)

    Sharma, Sunil Kumar; Kumar, Anil

    2017-05-01

    The rail-wheel interaction in a rail vehicle running at high speed results in large amplitude vibration of carbody that deteriorates the ride comfort of travellers. The role of suspension system is crucial to provide an acceptable level of ride performance. In this context, an existing rail vehicle is modelled in vertical, pitch and roll motions of carbody and bogies. Additionally, nonlinear stiffness and damping parameters of passive suspension system are defined based on experimental data. In the secondary vertical suspension system, a magneto-rheological (MR) damper is included to improve the ride quality and comfort. The parameters of MR damper depend on the current, amplitude and frequency of excitations. At different running speeds, three semi-active suspension strategies with MR damper are analysed for periodic track irregularity and the resulting performance indices are juxtaposed with the nonlinear passive suspension system. The disturbance rejection and force tracking damper controller algorithms are applied to control the desired force of MR damper. This study reveals that the vertical vibrations of a vehicle can be reduced significantly by using the proposed semi-active suspension strategies. Moreover, it naturally results in improved ride quality and passenger’s comfort in comparison to the existing passive system.

  14. Computer Simulation Study of Collective Phenomena in Dense Suspensions of Red Blood Cells under Shear

    CERN Document Server

    Krüger, Timm

    2012-01-01

    The rheology of dense red blood cell suspensions is investigated via computer simulations based on the lattice Boltzmann, the immersed boundary, and the finite element methods. The red blood cells are treated as extended and deformable particles immersed in the ambient fluid. In the first part of the work, the numerical model and strategies for stress evaluation are discussed. In the second part, the behavior of the suspensions in simple shear flow is studied for different volume fractions, particle deformabilities, and shear rates. Shear thinning behavior is recovered. The existence of a shear-induced transition from a tumbling to a tank-treading motion is demonstrated. The transition can be parameterized by a single quantity, namely the effective capillary number. It is the ratio of the suspension stress and the characteristic particle membrane stress. At the transition point, a strong increase in the orientational order of the red blood cells and a significant decrease of the particle diffusivity are obser...

  15. Disturbance observer based Takagi-Sugeno fuzzy control for an active seat suspension

    Science.gov (United States)

    Ning, Donghong; Sun, Shuaishuai; Zhang, Fei; Du, Haiping; Li, Weihua; Zhang, Bangji

    2017-09-01

    In this paper, a disturbance observer based Takagi-Sugeno (TS) fuzzy controller is proposed for an active seat suspension; both simulations and experiments have been performed verifying the performance enhancement and stability of the proposed controller. The controller incorporates closed-loop feedback control using the measured acceleration of the seat and deflection of the suspension; these two variables can be easily measured in practical applications, thus allowing the proposed controller to be robust and adaptable. A disturbance observer that can estimate the disturbance caused by friction, model simplification, and controller output error has also been used to compensate a H∞ state feedback controller. The TS fuzzy control method is applied to enhance the controller's performance by considering the variation of driver's weight during operation. The vibration of a heavy duty vehicle seat is largest in the frequency range between 2 Hz and 4 Hz, in the vertical direction; therefore, it is reasonable to focus on controlling low frequency vibration amplitudes and maintain the seat suspensions passivity at high frequency. Moreover, both the simulation and experimental results show that the active seat suspension with the proposed controller can effectively isolate unwanted vibration amplitudes below 4.5 Hz, when compared with a well-tuned passive seat suspension. The active controller has been further validated under bump and random road tests with both a 55 kg and a 70 kg loads. The bump road test demonstrated the controller has good transient response capabilities. The random road test result has been presented both in the time domain and the frequency domain. When with the above two loads, the controlled seat suspensions root-mean-square (RMS) accelerations were reduced by 45.5% and 49.5%, respectively, compared with a well-tuned passive seat suspension. The proposed active seat suspension controller has great potential and is very practical for application

  16. A Course in Fluid Mechanics of Suspensions.

    Science.gov (United States)

    Davis, Robert H.

    1989-01-01

    Discusses a course focusing on fluid mechanics and physical chemistry of suspensions. Describes the main themes of the lectures and includes a list of course outlines. Possible textbooks and many journal articles are listed. (YP)

  17. Experimental Evaluation of Mountain Bike Suspension Systems

    Directory of Open Access Journals (Sweden)

    J. Titlestad

    2003-01-01

    Full Text Available A significant distinction between competitive mountain bikes is whether they have a suspension system. Research studies indicate that a suspension system gives advantages, but it is difficult to quantify the benefits because they depend on so many variables, including the physiology and psychology of the cyclist, the roughness of the track and the design of the suspension system. A laboratory based test rig has been built that allows the number of variables in the system to be reduced and test conditions to be controlled. The test rig simulates regular impacts of the rear wheel with bumps in a rolling road. The physiological variables of oxygen consumption and heart rate were measured, together with speeds and forces at various points in the system. Physiological and mechanical test results both confirm a significant benefit in using a suspension system on the simulated rough track, with oxygen consumption reduced by around 30 % and power transmitted through the pedals reduced by 30 % to 60 %.

  18. Crust formation in drying colloidal suspensions

    KAUST Repository

    Style, R. W.; Peppin, S. S. L.

    2010-01-01

    and the equations of poroelasticity, while the equations of colloid physics govern processes in the suspension. We derive new equations describing this process, including unique boundary conditions coupling the two regions, yielding a moving-boundary model

  19. Enhancement of aerobic biodegradation in an oxygen-limiting environment using a saponin-based microbubble suspension

    International Nuclear Information System (INIS)

    Choi, Yong Ju; Kim, Young-Jin; Nam, Kyoungphile

    2009-01-01

    This study investigated the ability of a saponin-based microbubble suspension to enhance aerobic biodegradation of phenanthrene by subsurface delivery. As the microbubble suspension flowed through a sand column pressure buildup and release was repeatedly observed, which delivered oxygen to the less permeable regions. Burkholderia cepacia RPH1, a phenanthrene-degrading bacterium, was mainly transported in a suspended form in the microbubble suspension. When three pore volumes of the microbubble suspension containing B. cepacia RPH1 was introduced into a column contaminated with phenanthrene (100 mg/kg), the oxygen content declined to 5% from an initial value of 20% within 5 days and correspondingly, 34.4% of initial phenanthrene was removed in 8 days. The addition of two further three pore volumes enhanced the biodegradation efficiency by a factor of 2.2. Our data suggest that a saponin-based microbubble suspension could be a potential carrier for enhancing the aerobic biodegradation under an oxygen-limiting environment. - Microbubble suspension can enhance the phenanthrene biodegradation under an oxygen-limiting condition.

  20. Enhancement of aerobic biodegradation in an oxygen-limiting environment using a saponin-based microbubble suspension

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Yong Ju; Kim, Young-Jin [Department of Civil and Environmental Engineering, Seoul National University, Shillim-dong, Gwanak-gu, Seoul (Korea, Republic of); Nam, Kyoungphile, E-mail: kpnam@snu.ac.k [Department of Civil and Environmental Engineering, Seoul National University, Shillim-dong, Gwanak-gu, Seoul (Korea, Republic of)

    2009-08-15

    This study investigated the ability of a saponin-based microbubble suspension to enhance aerobic biodegradation of phenanthrene by subsurface delivery. As the microbubble suspension flowed through a sand column pressure buildup and release was repeatedly observed, which delivered oxygen to the less permeable regions. Burkholderia cepacia RPH1, a phenanthrene-degrading bacterium, was mainly transported in a suspended form in the microbubble suspension. When three pore volumes of the microbubble suspension containing B. cepacia RPH1 was introduced into a column contaminated with phenanthrene (100 mg/kg), the oxygen content declined to 5% from an initial value of 20% within 5 days and correspondingly, 34.4% of initial phenanthrene was removed in 8 days. The addition of two further three pore volumes enhanced the biodegradation efficiency by a factor of 2.2. Our data suggest that a saponin-based microbubble suspension could be a potential carrier for enhancing the aerobic biodegradation under an oxygen-limiting environment. - Microbubble suspension can enhance the phenanthrene biodegradation under an oxygen-limiting condition.

  1. Development of a falling ball rheometer with applications to opaque systems: measurements of the rheology of suspensions of rods

    International Nuclear Information System (INIS)

    Powell, R.L.; Mondy, L.A.; Stoker, G.G.; Milliken, W.J.; Graham, A.L.

    1989-01-01

    With falling ball rheometry, we have measured the apparent relative viscosity of suspensions of large, neutrally buoyant, rigid rods in a viscous Newtonian fluid, while approximately maintaining the rods in a randomly oriented configuration. A new technique for measuring the time of flight of a ball between two positions is used. This computerized technique, based upon an eddy current detector, enables us to determine the position of a metallic (nonmagnetic) ball falling through an opaque suspension, with high accuracy (less than 1.5% error). The rods for the suspensions had a nominal aspect ratio of 10 and experiments were carried out at a single volume fraction, 0.05. Two populations of rods were used to having nominal diameters of 1.5875 mm and 3.175 mm. To within the errors of these experiments, suspensions from both populations had the same relative viscosity, with the overall average being 1.457. This viscosity was significantly different from that of a similar suspension (volume fraction=0.05) of rods of nominal aspect ratio 20 and it agreed well with theoretical results for the viscosity of a dilute suspension of randomly oriented rods

  2. Increasing Possibilities of Nano suspension

    International Nuclear Information System (INIS)

    Sutradhar, K.B.; Khatun, S.; Luna, I.P.

    2013-01-01

    Nowadays, a very large proportion of new drug candidates emerging from drug discovery programmes are water insoluble and thus poorly bioavailable. To avoid this problem, nano technology for drug delivery has gained much interest as a way to improve the solubility problems. Nano refers to particles size range of 1-1000 nm. The reduction of drug particles into the submicron range leads to a significant increase in the dissolution rate and therefore enhances bioavailability. Nanosuspensions are part of nano technology. This interacts with the body at subcellular (i.e., molecular) scales with a high degree of specificity and can be potentially translated into targeted cellular and tissue-specific clinical applications designed to achieve maximal therapeutic efficacy with minimal side effects. Production of drugs as nanosuspensions can be developed for drug delivery systems as an oral formulation and no noral administration. Here, this review describes the methods of pharmaceutical nano suspension production including advantages and disadvantages, potential benefits, characterization tests, and pharmaceutical applications in drug delivery

  3. Suspension scheme for fuel pin

    International Nuclear Information System (INIS)

    Butts, C.E.; Gray, H.C.

    1975-01-01

    A description is presented of a nuclear fuel pin suspension arrangement comprising, in combination, a rod; a first beam member connected to said rod at one end; a plurality of parallel-spaced slidable fuel support plates attached to said first beam member, the longitudinal axis of first beam member being perpendicular to the longitudinal axis of each of said fuel support plates, a first coupling means disposed along the length of the first beam member for permitting slidable fuel support plates parallel movement with respect to the longitudinal axis of said first beam member, a second coupling means located at one end of each of slidable fuel plates for slidably engaging first coupling means of first beam member, a second beam member connected to the other end of each of parallel-spaced slidable fuel support plates and providing an extension, second beam member being provided with a third coupling means disposed along the length of second beam member at one end thereof; and a plurality of fuel pins provided with a fourth coupling means located at one end of each fuel pin for slidably engaging third coupling means of second beam member to permit each fuel pin parallel movement with respect to the longitudinal axis of second beam member. (U.S.)

  4. Compressed Air Production Using Vehicle Suspension

    OpenAIRE

    Ninad Arun Malpure; Sanket Nandlal Bhansali

    2015-01-01

    Abstract Generally compressed air is produced using different types of air compressors which consumes lot of electric energy and is noisy. In this paper an innovative idea is put forth for production of compressed air using movement of vehicle suspension which normal is wasted. The conversion of the force energy into the compressed air is carried out by the mechanism which consists of the vehicle suspension system hydraulic cylinder Non-return valve air compressor and air receiver. We are co...

  5. Applying radiation

    International Nuclear Information System (INIS)

    Mallozzi, P.J.; Epstein, H.M.; Jung, R.G.; Applebaum, D.C.; Fairand, B.P.; Gallagher, W.J.; Uecker, R.L.; Muckerheide, M.C.

    1979-01-01

    The invention discloses a method and apparatus for applying radiation by producing X-rays of a selected spectrum and intensity and directing them to a desired location. Radiant energy is directed from a laser onto a target to produce such X-rays at the target, which is so positioned adjacent to the desired location as to emit the X-rays toward the desired location; or such X-rays are produced in a region away from the desired location, and are channeled to the desired location. The radiant energy directing means may be shaped (as with bends; adjustable, if desired) to circumvent any obstruction between the laser and the target. Similarly, the X-ray channeling means may be shaped (as with fixed or adjustable bends) to circumvent any obstruction between the region where the X-rays are produced and the desired location. For producing a radiograph in a living organism the X-rays are provided in a short pulse to avoid any blurring of the radiograph from movement of or in the organism. For altering tissue in a living organism the selected spectrum and intensity are such as to affect substantially the tissue in a preselected volume without injuring nearby tissue. Typically, the selected spectrum comprises the range of about 0.1 to 100 keV, and the intensity is selected to provide about 100 to 1000 rads at the desired location. The X-rays may be produced by stimulated emission thereof, typically in a single direction

  6. Flow-induced structure in colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Vermant, J [Department of Chemical Engineering, K U Leuven, W de Croylaan 46, B-3001 Leuven (Belgium); Solomon, M J [Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109-2136 (United States)

    2005-02-02

    We review the sequences of structural states that can be induced in colloidal suspensions by the application of flow. Structure formation during flow is strongly affected by the delicate balance among interparticle forces, Brownian motion and hydrodynamic interactions. The resulting non-equilibrium microstructure is in turn a principal determinant of the suspension rheology. Colloidal suspensions with near hard-sphere interactions develop an anisotropic, amorphous structure at low dimensionless shear rates. At high rates, clustering due to strong hydrodynamic forces leads to shear thickening rheology. Application of steady-shear flow to suspensions with repulsive interactions induces a rich sequence of transitions to one-, two-and three-dimensional order. Oscillatory-shear flow generates metastable ordering in suspensions with equilibrium liquid structure. On the other hand, short-range attractive interactions can lead to a fluid-to-gel transition under quiescent suspensions. Application of flow leads to orientation, breakup, densification and spatial reorganization of aggregates. Using a non-Newtonian suspending medium leads to additional possibilities for organization. We examine the extent to which theory and simulation have yielded mechanistic understanding of the microstructural transitions that have been observed. (topical review)

  7. Statistical examination of particle in a turbulent, non-dilute particle suspension flow experimental measurements

    International Nuclear Information System (INIS)

    Souza, R.C.; Jones, B.G.

    1986-01-01

    An experimental study of particles suspended in fully developed turbulent water flow in a vertical pipe was done. Three series of experiments were conducted to investigate the statistical behaviour of particles in nondilute turbulent suspension flow, for two particle densities and particle sizes, and for several particle volume loadings ranging from 0 to 1 percent. The mean free fall velocity of the particles was determined at these various particle volume loadings, and the phenomenon of cluster formation was observed. The precise volume loading which gives the maximum relative settling velocity was observed to depend on particle density and size. (E.G.) [pt

  8. Dispersion of Sound in Dilute Suspensions with Nonlinear Particle Relaxation

    Science.gov (United States)

    Kandula, Max

    2010-01-01

    The theory accounting for nonlinear particle relaxation (viscous and thermal) has been applied to the prediction of dispersion of sound in dilute suspensions. The results suggest that significant deviations exist for sound dispersion between the linear and nonlinear theories at large values of Omega(Tau)(sub d), where Omega is the circular frequency, and Tau(sub d) is the Stokesian particle relaxation time. It is revealed that the nonlinear effect on the dispersion coefficient due to viscous contribution is larger relative to that of thermal conduction

  9. Effect of different vehicles in carrageenan suspension on the rate of the inflammatory response of chicks

    Directory of Open Access Journals (Sweden)

    Alda Maria Backx Noronha Madeira

    1995-12-01

    Full Text Available This paper describes the pattern of edema, increased vascular permeability and cellular exudation elicited by the injection of different carrageenan suspensions into the foot pad of 80 male chicks, three to four-week old. Carrageenan suspensions at 0.5% were prepared in: Ringer Locke solution (RL, glucose aqueous solution 0.1% (G, demineralized water (W or phosphate buffered saline (PBS. The foot pad volume and vascular permeability were evaluated by pletismography and by Evans blue extravasation, respectively, before and at 0:15, 0:30, 1:00, 1:30, 2:00, 2:30, 3:00, 3:30 and 4:00 hours after injury. Cellular exudation was observed in thin sections of stained tissue 0:30, 1:30, 2:30 and 4:00 hours after injection of the carrageenan or vehicle only. The inflammatory response varied according to the carrageenan suspension used. Suspension C/PBS induced a less intense inflammatory response in foot pads of chicks than C/W, C/G and C/RL suspensions.

  10. Rheological study of two-dimensional very anisometric colloidal particle suspensions: from shear-induced orientation to viscous dissipation.

    Science.gov (United States)

    Philippe, A M; Baravian, C; Bezuglyy, V; Angilella, J R; Meneau, F; Bihannic, I; Michot, L J

    2013-04-30

    In the present study, we investigate the evolution with shear of the viscosity of aqueous suspensions of size-selected natural swelling clay minerals for volume fractions extending from isotropic liquids to weak nematic gels. Such suspensions are strongly shear-thinning, a feature that is systematically observed for suspensions of nonspherical particles and that is linked to their orientational properties. We then combined our rheological measurements with small-angle X-ray scattering experiments that, after appropriate treatment, provide the orientational field of the particles. Whatever the clay nature, particle size, and volume fraction, this orientational field was shown to depend only on a nondimensional Péclet number (Pe) defined for one isolated particle as the ratio between hydrodynamic energy and Brownian thermal energy. The measured orientational fields were then directly compared to those obtained for infinitely thin disks through a numerical computation of the Fokker-Plank equation. Even in cases where multiple hydrodynamic interactions dominate, qualitative agreement between both orientational fields is observed, especially at high Péclet number. We have then used an effective approach to assess the viscosity of these suspensions through the definition of an effective volume fraction. Using such an approach, we have been able to transform the relationship between viscosity and volume fraction (ηr = f(φ)) into a relationship that links viscosity with both flow and volume fraction (ηr = f(φ, Pe)).

  11. Damping and tuning of the fibre violin modes in monolithic silica suspensions

    International Nuclear Information System (INIS)

    Gossler, S; Cagnoli, G; Crooks, D R M; Lueck, H; Rowan, S; Smith, J R; Strain, K A; Hough, J; Danzmann, K

    2004-01-01

    High Q mirror suspensions are a key element of the advanced interferometric gravitational-wave detectors. In December 2002 the last of the final interferometer optics of GEO 600 were monolithically suspended, using fused silica fibres. The violin modes of the suspension fibres can have Q greater than 10 8 and can therefore interfere with the interferometer length control servo. Hence, the violin modes need to be damped, without degrading the pendulum Q itself. Furthermore, the frequency spread of the fibres used has to be small to allow for high Q notch filtering in the length control servo. The requirements for the violin modes of the two GEO 600 inboard suspensions are Q 6 for the fundamental and Q 6 for the first harmonic mode, respectively. The frequency spread should not exceed 10% within one mode. To accomplish that, two sections of the fibres were coated with amorphous Teflon. By applying the coating, the Q of the relevant modes can be degraded to the desired values and furthermore, the frequencies of these modes can be tuned almost independently with a good accuracy over a wide range. After welding the fibres in the monolithic suspension, a corrective coating was applied to some fibres, to compensate for the frequency spread due to the tension spread of the four fibres within a suspension. We present the method and the results achieved

  12. Damping and tuning of the fibre violin modes in monolithic silica suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Gossler, S [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany); Cagnoli, G [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Crooks, D R M [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Lueck, H [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany); Rowan, S [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Smith, J R [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany); Strain, K A [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Hough, J [Department of Physics and Astronomy, Institute for Gravitational Research, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Danzmann, K [Max-Planck-Institute for Gravitational Physics (Albert-Einstein-Institute) and University of Hannover, Callinstr 38, D-30167 Hannover (Germany)

    2004-03-07

    High Q mirror suspensions are a key element of the advanced interferometric gravitational-wave detectors. In December 2002 the last of the final interferometer optics of GEO 600 were monolithically suspended, using fused silica fibres. The violin modes of the suspension fibres can have Q greater than 10{sup 8} and can therefore interfere with the interferometer length control servo. Hence, the violin modes need to be damped, without degrading the pendulum Q itself. Furthermore, the frequency spread of the fibres used has to be small to allow for high Q notch filtering in the length control servo. The requirements for the violin modes of the two GEO 600 inboard suspensions are Q < 3 x 10{sup 6} for the fundamental and Q < 2 x 10{sup 6} for the first harmonic mode, respectively. The frequency spread should not exceed 10% within one mode. To accomplish that, two sections of the fibres were coated with amorphous Teflon. By applying the coating, the Q of the relevant modes can be degraded to the desired values and furthermore, the frequencies of these modes can be tuned almost independently with a good accuracy over a wide range. After welding the fibres in the monolithic suspension, a corrective coating was applied to some fibres, to compensate for the frequency spread due to the tension spread of the four fibres within a suspension. We present the method and the results achieved.

  13. Stability of extemporaneously prepared sodium phenylbutyrate oral suspensions.

    Science.gov (United States)

    Caruthers, Regine L; Johnson, Cary E

    2007-07-15

    In an effort to minimize barriers to compliance and adherence and to improve the accuracy of dosage measurement, sugar-containing and sugar-free sodium phenylbutyrate suspensions were formulated, and the stability of these products over a 90-day period was determined. An oral suspension of sodium phenylbutyrate 200 mg/mL was prepared by thoroughly grinding 12 g of Sodium Phenylbutyrate Powder, USP, in a glass mortar. Thirty milliliters of Ora-Plus and 30 mL of either Ora-Sweet or Ora-Sweet SF were mixed and added to the powder to make a final volume of 60 mL. Three identical samples of each formulation were prepared and placed in 2-oz amber plastic bottles with child-resistant caps and were stored at room temperature. A 500-microL sample was withdrawn from each of the six bottles with a micropipette immediately after preparation and at 7, 14, 28, 60, and 90 days. After further dilution to an expected concentration of 100 microg/mL with the mobile phase, the samples were assayed by high-performance liquid chromatography. Stability was defined as the retention of at least 90% of the initial concentration. At least 95% of the initial sodium phenylbutyrate concentration remained throughout the 90-day study period in both preparations. There were no detectable changes in color, odor, taste, and pH and no visible microbial growth in any sample. Extemporaneously compounded suspensions of sodium phenylbutyrate, 200 mg/mL, in a 1:1 mixture of Ora-Plus and Ora-Sweet or Ora-Sweet SF were stable for at least 90 days when stored in 2-oz amber plastic bottles at room temperature.

  14. Numerical study of heat and mass transfer in inertial suspensions in pipes.

    Science.gov (United States)

    Niazi Ardekani, Mehdi; Brandt, Luca

    2017-11-01

    Controlling heat and mass transfer in particulate suspensions has many important applications such as packed and fluidized bed reactors and industrial dryers. In this work, we study the heat and mass transfer within a suspension of spherical particles in a laminar pipe flow, using the immersed boundary method (IBM) to account for the solid fluid interactions and a volume of fluid (VoF) method to resolve temperature equation both inside and outside of the particles. Tracers that follow the fluid streamlines are considered to investigate mass transfer within the suspension. Different particle volume fractions 5, 15, 30 and 40% are simulated for different pipe to particle diameter ratios: 5, 10 and 15. The preliminary results quantify the heat and mass transfer enhancement with respect to a single-phase laminar pipe flow. We show in particular that the heat transfer from the wall saturates for volume fractions more than 30%, however at high particle Reynolds numbers (small diameter ratios) the heat transfer continues to increase. Regarding the dispersion of tracer particles we show that the diffusivity of tracers increases with volume fraction in radial and stream-wise directions however it goes through a peak at 15% in the azimuthal direction. European Research Council, Grant No. ERC-2013-CoG- 616186, TRITOS; SNIC (the Swedish National Infrastructure for Computing).

  15. DC electrophoresis and viscosity of realistic salt-free concentrated suspensions: non-equilibrium dissociation-association processes.

    Science.gov (United States)

    Ruiz-Reina, Emilio; Carrique, Félix; Lechuga, Luis

    2014-03-01

    Most of the suspensions usually found in industrial applications are concentrated, aqueous and in contact with the atmospheric CO2. The case of suspensions with a high concentration of added salt is relatively well understood and has been considered in many studies. In this work we are concerned with the case of concentrated suspensions that have no ions different than: (1) those stemming from the charged colloidal particles (the added counterions, that counterbalance their surface charge); (2) the H(+) and OH(-) ions from water dissociation, and (3) the ions generated by the atmospheric CO2 contamination. We call this kind of systems "realistic salt-free suspensions". We show some theoretical results about the electrophoretic mobility of a colloidal particle and the electroviscous effect of realistic salt-free concentrated suspensions. The theoretical framework is based on a cell model that accounts for particle-particle interactions in concentrated suspensions, which has been successfully applied to many different phenomena in concentrated suspensions. On the other hand, the water dissociation and CO2 contamination can be described following two different levels of approximation: (a) by local equilibrium mass-action equations, because it is supposed that the reactions are so fast that chemical equilibrium is attained everywhere in the suspension, or (b) by non-equilibrium dissociation-association kinetic equations, because it is considered that some reactions are not rapid enough to ensure local chemical equilibrium. Both approaches give rise to different results in the range from dilute to semidilute suspensions, causing possible discrepancies when comparing standard theories and experiments concerning transport properties of realistic salt-free suspensions. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Stability and uniformity of extemporaneous preparations of voriconazole in two liquid suspension vehicles at two storage temperatures.

    Science.gov (United States)

    Nguyen, Kyvan Q; Hawkins, Michelle G; Taylor, Ian T; Wiebe, Valerie J; Tell, Lisa A

    2009-07-01

    To determine the stability and distribution of voriconazole in 2 extemporaneously prepared (compounded) suspensions stored for 30 days at 2 temperatures. Voriconazole suspensions (40 mg/mL) compounded from commercially available 200-mg tablets suspended in 1 of 2 vehicles. One vehicle contained a commercially available suspending agent and a sweetening syrup in a 1:1 mixture (SASS). The other vehicle contained the suspending agent with deionized water in a 3:1 mixture (SADI). Voriconazole suspensions (40 mg/mL in 40-mL volumes) were compounded on day 0 and stored at room temperature (approx 21 degrees C) or refrigerated (approx 5 degrees C). To evaluate distribution, room-temperature aliquots of voriconazole were measured immediately after preparation. Refrigerated aliquots were measured after 3 hours of refrigeration. To evaluate stability, aliquots from each suspension were measured at approximately 7-day intervals for up to 30 days. Voriconazole concentration, color, odor, opacity, and pH were measured, and aerobic and anaerobic bacterial cultures were performed at various points. Drug distribution was uniform (coefficient of variation, suspensions. On day 0, 87.8% to 93.0% of voriconazole was recovered; percentage recovery increased to between 95.1% and 100.8% by day 7. On subsequent days, up to day 30, percentage recovery was stable (> 90%) for all suspensions. The pH of each suspension did not differ significantly throughout the 30-day period. Storage temperature did not affect drug concentrations at any time, nor was bacterial growth obtained. Extemporaneously prepared voriconazole in SASS and SADI resulted in suspensions that remained stable for at least 30 days. Refrigerated versus room-temperature storage of the suspensions had no effect on drug stability.

  17. [Suspension laryngoscopic surgery for laryngotracheal stenosis of 32 cases].

    Science.gov (United States)

    Wang, Chunyan; Qin, Yong; Xiao, Shuifang

    2014-08-01

    To investigate the efficacy of suspension laryngoscopic surgery for benign laryngotracheal stenosis (LTS). Thirty-two patients (aged from 5 to 70 years with a median of 36 years) with benign LTS were studied retrospectively who were treated by suspension laryngoscopic surgery with or without assistance of CO₂ Laser for LTS. Stents were placed in 17 cases. Among 32 patients, 13 cases were with LST in Cotton I, 8 cases in Cotton II, and 11 cases in Cotton III; 23 were with single level narrow, and 9 cases with multi-level narrow; the average narrow length was 1.3 cm and the average diameter at maximum stenosis was 0.5 cm; and 19 cases underwent tracheostomy before surgery. Follow-up period ranged from 1 to 18 years with median time of 10 years. Twenty-six patients (81.2%) were successfully decannulated with good airway patency and effective phonation. Six cases failed and 1 case of them was changed to open surgery. Among 17 cases with stent placement, 4 cases were applied additionally with T tube (effective rate of 50.0%), 1 case with laryngeal keel, 12 cases with stents alone (effective rate of 66.7%). Stent-related complications occurred in 2 cases. Patients with cotton I-II had a successful rate of 100% (21/21), while patients with Cotton III showed poor effectiveness (5/11), with a statistical significant difference between two groups (χ² = 14.098, P = 0.001). The patients with single level LTS were successfully treated by suspension laryngoscopic surgery with 100% successful rate (23/23), while the patients with multi-level LTS showed poor effectiveness (3/9), with a statistical significant difference between two groups (χ² = 18.872, P = 0.000) . Suspension laryngoscopic microsurgery can treat single level LTS with good results and also can be used as a pre-surgery in treatment of multi-level LTS with the virtue of minimal trauma and short recovery time. Application of stents can be helpful for suspension laryngoscope surgery for LST.

  18. 21 CFR 1301.36 - Suspension or revocation of registration; suspension of registration pending final order...

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Suspension or revocation of registration; suspension of registration pending final order; extension of registration pending final order. 1301.36... registration pending final order; extension of registration pending final order. (a) For any registration...

  19. Suspension, a Wake-Up Call: Rural Educators' Attitudes toward Suspension.

    Science.gov (United States)

    Henderson, Joan; Friedland, Billie

    Data from the West Virginia Department of Education reveals that from September 1991 to January 1992, school districts reported 18,915 out-of-school suspensions involving 12,997 students. In 1995, the West Virginia State Legislature enacted the Safe Schools Act, which specifically mandates suspension for no less than 12 consecutive months for…

  20. Actuator and sensor selection for an active vehicle suspension aimed at robust performance

    NARCIS (Netherlands)

    Wal, van de M.M.J.; Philips, P.P.H.H.; Jager, de A.G.

    1998-01-01

    A recently presented method for actuator and sensor selection for linear control systems is applied and evaluated for an active vehicle suspension control problem. The aim is to eliminate the actuator/sensor combinations for which no controller exists that achieves a specified level of robust

  1. Minimally invasive brow suspension for facial paralysis.

    Science.gov (United States)

    Costantino, Peter D; Hiltzik, David H; Moche, Jason; Preminger, Aviva

    2003-01-01

    To report a new technique for unilateral brow suspension for facial paralysis that is minimally invasive, limits supraciliary scar formation, does not require specialized endoscopic equipment or expertise, and has proved to be equal to direct brow suspension in durability and symmetry. Retrospective survey of a case series of 23 patients between January 1997 and December 2000. Metropolitan tertiary care center. Patients with head and neck tumors and brow ptosis caused by facial nerve paralysis. The results of the procedure were determined using the following 3-tier rating system: outstanding (excellent elevation and symmetry); acceptable (good elevation and fair symmetry); and unacceptable (loss of elevation). The results were considered outstanding in 12 patients, acceptable in 9 patients, and unacceptable in only 1 patient. One patient developed a hematoma, and 1 patient required a secondary adjustment. The technique has proved to be superior to standard brow suspension procedures with regard to scar formation and equal with respect to facial symmetry and suspension. These results have caused us to abandon direct brow suspension and to use this minimally invasive method in all cases of brow ptosis due to facial paralysis.

  2. Pitched Blade Turbine Efficiency at Particle Suspension

    Directory of Open Access Journals (Sweden)

    D. Ceres

    2010-01-01

    Full Text Available Mixing suspensions is a very important hydraulic operation. The pitched six-blade turbine is a widely-used axial-flow impeller. This paper deals with effect relative impeller size and particle content on theefficiency of a pitched six-blade turbine at particle suspension. Two pitched six-blade turbines were used in model measurements of just suspension impeller speed. The ratios of the vessel to agitator diameter D/d were 3 and 4.5. The measurements were carried out in a dish-bottomed vessel 300 mm in diameter. The just suspension impeller speeds were measured using an electrochemical method, and were checked visually. A 2.5 % NaCl water solution was used as the liquid phase, and glass particles with four equivalent diameters between 0.18 and 0.89 mmand volumetric concentration from 2.5 % to 40% were usedasthesolid phase. The criterion values πs=Po√Fr'3(d/D7 were calculated from the particle suspension and power consumption measurements. The dependencies of πs on particle content cv show that larger agitators are more efficient for higher particle content.

  3. THE APPLICATION OF DETERMINATION METHOD OF DYNAMIC PROPERTIES OF TRACK SUSPENSION IN LABVIEW

    Directory of Open Access Journals (Sweden)

    Jan WARCZEK

    2015-03-01

    Full Text Available The article presents the results of simulation tests, which aim was to validate the method of determining the damping characteristics of the suspension vehicle. The developed method was used for the implementation of the program in LabView environment. The study used the results of simulations carried out on the DOF model of a truck suspension. Ultimately, the presented method and its version in use as a program running on the Windows platform is to be applied in the diagnosis of vehicles with a maximum permissible weight of over 3.5 tonnes.

  4. Studies of the setting behavior of cement suspensions

    International Nuclear Information System (INIS)

    Rudolph, G.; Luo, S.; Vejmelka, P.; Koester, R.

    1983-10-01

    The design of process for cementation of radioactive waste solutions is determined not only by the quality of the final product but also by the behavior of the cement grout before and during setting. For these reasons quantitative investigations were performed on the characteristics of the cement suspensions considered for solidification of intermediate-level liquid wastes which are composed mainly of cement, bentonite, simulated waste solution, and water. Particular interest was given to the differences in behavior of the various types of cement. The parameters investigated include viscosity, bleeding, volume change during setting, influence of compacting by vibration, time of setting, heat of hydration. At the end of the report the merits and drawbacks of the different cements are tabulated. These data may serve as a decision aid in selecting an appropriate type of cement

  5. On the behaviour of gelled fibre suspensions in steady shear

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, Bettina [Unilever Corporate Research, Bedford (United Kingdom); University of Nottingham, Division of Food Sciences, Loughborough (United Kingdom); White, Duncan; Melrose, John R.; Frith, William J. [Unilever Corporate Research, Bedford (United Kingdom)

    2007-03-15

    The shear rheological properties of suspensions of gelled agar fibres in a low viscosity Newtonian matrix fluid were investigated. Two classes of fibres, low aspect ratio fibres and high aspect ratio fibres with an aspect ratio of the order of 10 and 100 respectively were included in the investigations. For all fibre phase volumes investigated, from as low as 0.01 upwards, the flow curves are characterised by an apparent yield stress followed by shear-thinning which was independent of the fibre aspect ratio. Based on our analysis of the flow curves, we conclude that the high aspect ratio fibres behave like flexible threads in contrast to the low aspect ratio fibres whose high shear relative viscosity is successfully described by a relation for long rigid rods. These findings are supported by flow visualisation using an optical shearing stage coupled to a light microscope. (orig.)

  6. Modeling Suspension and Continuation of a Process

    Directory of Open Access Journals (Sweden)

    Oleg Svatos

    2012-04-01

    Full Text Available This work focuses on difficulties an analyst encounters when modeling suspension and continuation of a process in contemporary process modeling languages. As a basis there is introduced general lifecycle of an activity which is then compared to activity lifecycles supported by individual process modeling languages. The comparison shows that the contemporary process modeling languages cover the defined general lifecycle of an activity only partially. There are picked two popular process modeling languages and there is modeled real example, which reviews how the modeling languages can get along with their lack of native support of suspension and continuation of an activity. Upon the unsatisfying results of the contemporary process modeling languages in the modeled example, there is presented a new process modeling language which, as demonstrated, is capable of capturing suspension and continuation of an activity in much simpler and precise way.

  7. Phagocytosis in phosphate chromium (III) suspensions

    International Nuclear Information System (INIS)

    Cruz-Arencibia, Jorge; Fano Machín, Yoiz; Cruz-Morales, Ahmed; Tamayo Fuente, Radamés; Morín-Zorrilla, José

    2015-01-01

    Phagocytosis in vivo and in vitro of a suspension of chromic phosphate (III) labeled with 51 Cr and 32 P is studied. The radioactive particles dispersed in a media of 2 % gelatin in acetate buffer pH 4-4.5 have a predominant size of 0.8 μm and 5 μm. According with biodistribution experiments in rats after 30 minutes near the 80 % of radioactivity is registered in the liver, probably associated with phagocytosis of the particles by liver Kupffer cells. Is also showed that the suspension particles are phagocytized in vitro by mouse peritoneal macrophages. This facts indicate that the studied suspension have appropriate characteristics to be used in radiosynoviorthesis according to the principal action mechanism described for this procedure, particles phagocytosis by cells present in the inflamed synovium. (author)

  8. Crust formation in drying colloidal suspensions

    KAUST Repository

    Style, R. W.

    2010-06-30

    During the drying of colloidal suspensions, the desiccation process causes the suspension near the air interface to consolidate into a connected porous matrix or crust. Fluid transport in the porous medium is governed by Darcy\\'s law and the equations of poroelasticity, while the equations of colloid physics govern processes in the suspension. We derive new equations describing this process, including unique boundary conditions coupling the two regions, yielding a moving-boundary model of the concentration and stress profiles during drying. A solution is found for the steady-state growth of a nedimensional crust during constant evaporation rate from the surface. The solution is used to demonstrate the importance of the system boundary conditions on stress profiles and diffusivity in a drying crust. © 2011 The Royal Society.

  9. Improving the cooling performance of electrical distribution transformer using transformer oil – Based MEPCM suspension

    OpenAIRE

    Mushtaq Ismael Hasan

    2017-01-01

    In this paper the electrical distribution transformer has been studied numerically and the effect of outside temperature on its cooling performance has been investigated. The temperature range studied covers the hot climate regions. 250 KVA distribution transformer is chosen as a study model. A novel cooling fluid is proposed to improve the cooling performance of this transformer, transformer oil-based microencapsulated phase change materials suspension is used with volume concentration (5–25...

  10. Performance Testing of Suspension Plasma Sprayed Thermal Barrier Coatings Produced with Varied Suspension Parameters

    Directory of Open Access Journals (Sweden)

    Nicholas Curry

    2015-07-01

    Full Text Available Suspension plasma spraying has become an emerging technology for the production of thermal barrier coatings for the gas turbine industry. Presently, though commercial systems for coating production are available, coatings remain in the development stage. Suitable suspension parameters for coating production remain an outstanding question and the influence of suspension properties on the final coatings is not well known. For this study, a number of suspensions were produced with varied solid loadings, powder size distributions and solvents. Suspensions were sprayed onto superalloy substrates coated with high velocity air fuel (HVAF -sprayed bond coats. Plasma spray parameters were selected to generate columnar structures based on previous experiments and were maintained at constant to discover the influence of the suspension behavior on coating microstructures. Testing of the produced thermal barrier coating (TBC systems has included thermal cyclic fatigue testing and thermal conductivity analysis. Pore size distribution has been characterized by mercury infiltration porosimetry. Results show a strong influence of suspension viscosity and surface tension on the microstructure of the produced coatings.

  11. Rheological behavior and stability of ciprofloxacin suspension: Impact of structural vehicles and flocculating agent

    Directory of Open Access Journals (Sweden)

    Eskandar Moghimipour

    2013-01-01

    Full Text Available Ciprofloxacin is a fluoroquinolone and is used against a broad spectrum of gram-negative and gram-positive bacteria. The aim of the study is to investigate the effect of structural vehicles and other formulating factors on physical stability and rheological behavior of ciprofloxacin suspension. To formulate the suspensions, the effect of glycerin and polysorbate 80 as wetting agents was evaluated. Then to achieve controlled flocculation, different concentrations of sodium chloride and calcium chloride were added. After choosing suitable wetting and flocculating agents, structural vehicles such as sodium carboxyl methyl cellulose (NaCMC, hydroxypropylmethylcellulose (HPMC and Veegum were evaluated. Physical stability parameters such as sedimentation volume, the degree of flocculation and the ease of redispersion of the suspensions and growth of crystals were evaluated. After incorporation of structural vehicles, the rheological properties of formulations containing were also studied to find out their rheological behavior. According to the results, suspension containing glycerin (0.2% w/v and sodium chloride (0.05% w/v as wetting agent and flocculating agent, respectively, were the most stable formulations regarding their F and N. Microscopic observations showed the growth of crystals in ciprofloxacin suspension in formulation without excipients and the minimum amount of crystal growth was seen in suspension containing NaCMC (0.25% w/v, Veegum (0.1% w/v and NaCl (0.05% w/v. Rheological studies showed that almost all of the formulations had psuedoplastic behavior with different degree of thixotropy. The formulation containing NaCMC (0.25% w/v, Veegum (0.1% w/v and NaCl (0.05% w/v was the most stable formulation. It may be concluded that by altering the amount ratios of formulation factors, the best rheological behavior and the most proper thixotropy may be achieved.

  12. Rheological behavior and stability of ciprofloxacin suspension: Impact of structural vehicles and flocculating agent.

    Science.gov (United States)

    Moghimipour, Eskandar; Rezaee, Saeed; Salimi, Anayatollah; Asadi, Elham; Handali, Somayeh

    2013-07-01

    Ciprofloxacin is a fluoroquinolone and is used against a broad spectrum of gram-negative and gram-positive bacteria. The aim of the study is to investigate the effect of structural vehicles and other formulating factors on physical stability and rheological behavior of ciprofloxacin suspension. To formulate the suspensions, the effect of glycerin and polysorbate 80 as wetting agents was evaluated. Then to achieve controlled flocculation, different concentrations of sodium chloride and calcium chloride were added. After choosing suitable wetting and flocculating agents, structural vehicles such as sodium carboxyl methyl cellulose (NaCMC), hydroxypropylmethylcellulose (HPMC) and Veegum were evaluated. Physical stability parameters such as sedimentation volume, the degree of flocculation and the ease of redispersion of the suspensions and growth of crystals were evaluated. After incorporation of structural vehicles, the rheological properties of formulations containing were also studied to find out their rheological behavior. According to the results, suspension containing glycerin (0.2% w/v) and sodium chloride (0.05% w/v) as wetting agent and flocculating agent, respectively, were the most stable formulations regarding their F and N. Microscopic observations showed the growth of crystals in ciprofloxacin suspension in formulation without excipients and the minimum amount of crystal growth was seen in suspension containing NaCMC (0.25% w/v), Veegum (0.1% w/v) and NaCl (0.05% w/v). Rheological studies showed that almost all of the formulations had psuedoplastic behavior with different degree of thixotropy. The formulation containing NaCMC (0.25% w/v), Veegum (0.1% w/v) and NaCl (0.05% w/v) was the most stable formulation. It may be concluded that by altering the amount ratios of formulation factors, the best rheological behavior and the most proper thixotropy may be achieved.

  13. Suspension Hydrogen Reduction of Iron Oxide Concentrates

    Energy Technology Data Exchange (ETDEWEB)

    H.Y. Sohn

    2008-03-31

    The objective of the project is to develop a new ironmaking technology based on hydrogen and fine iron oxide concentrates in a suspension reduction process. The ultimate objective of the new technology is to replace the blast furnace and to drastically reduce CO2 emissions in the steel industry. The goals of this phase of development are; the performance of detailed material and energy balances, thermochemical and equilibrium calculations for sulfur and phosphorus impurities, the determination of the complete kinetics of hydrogen reduction and bench-scale testing of the suspension reduction process using a large laboratory flash reactor.

  14. Intelligent systems of the vehicles’ suspension

    Science.gov (United States)

    Yurlin, D.

    2018-02-01

    The article is devoted to the current condition of car’s active suspension system. It presents the tendencies in development of the active systems of suspension system, adjustable elements incorporated in them and the companies succeeded in designing such systems. It also mirrors the problem of impact of active systems on car’s safety and their importance for the driver. Advantages and disadvantages of the most common types of active elements are being described, analyzed and compared. The author concludes about the perspectives of these systems’ development.

  15. Analysis of Driving Safety Criteria Based on National Regulations for the Suspension Systems of NGVs

    Directory of Open Access Journals (Sweden)

    Ronald Mauricio Martinod

    2015-01-01

    Full Text Available The work analyses the technical evaluation process of the suspension system for vehicles that have been adapted to natural-gas-fuelled engines from power light-duty gasoline, and diesel vehicles; this evaluation is done through a mechanical review established by national regulations. The development of this analysis is focused on establishing the relationship between the natural-gas-fuelled equipment and the dynamic effect caused by the extra-weight, according to two measuring criteria that determine the safety and driving comfort, these are: (i tire-road adhesion index; and (ii tire excitation phase angle. The paper also proposes new elements that can be added to the current national regulations and that are currently applied to assess the suspension of natural gas vehicles, recorded using a test standard benchmark for the evaluation of the suspension.

  16. Sky-Hook Control and Kalman Filtering in Nonlinear Model of Tracked Vehicle Suspension System

    Directory of Open Access Journals (Sweden)

    Jurkiewicz Andrzej

    2017-09-01

    Full Text Available The essence of the undertaken topic is application of the continuous sky-hook control strategy and the Extended Kalman Filter as the state observer in the 2S1 tracked vehicle suspension system. The half-car model of this suspension system consists of seven logarithmic spiral springs and two magnetorheological dampers which has been described by the Bingham model. The applied continuous sky-hook control strategy considers nonlinear stiffness characteristic of the logarithmic spiral springs. The control is determined on estimates generated by the Extended Kalman Filter. Improve of ride comfort is verified by comparing simulation results, under the same driving conditions, of controlled and passive vehicle suspension systems.

  17. Scaling of the space-time correlation function of particle currents in a suspension of hard-sphere-like particles: exposing when the motion of particles is Brownian.

    Science.gov (United States)

    van Megen, W; Martinez, V A; Bryant, G

    2009-12-18

    The current correlation function is determined from dynamic light scattering measurements of a suspension of particles with hard spherelike interactions. For suspensions in thermodynamic equilibrium we find scaling of the space and time variables of the current correlation function. This finding supports the notion that the movement of suspended particles can be described in terms of uncorrelated Brownian encounters. However, in the metastable fluid, at volume fractions above freezing, this scaling fails.

  18. Anomalous intrinsic viscosity of octadecylamine-functionalised carbon nanotubes in suspension.

    Science.gov (United States)

    Donovan, K J; Scott, K

    2013-06-28

    Single walled carbon nanotubes, SWCNTs, are used as a model cylinder of nanoscopic dimensions for testing rheological theories of how addition of cylindrical particles affects the viscosity of a suspension of such particles. Using the rate of growth of the accompanying induced linear dichroism following application of an applied electric field, the dynamics of carbon nanotube alignment is studied in suspensions of octadecylamine functionalised single walled carbon nanotubes, ODA-SWCNTs, in 1,2 dichloroethane. From such measurements the viscosity of the suspension is measured as the concentration of the suspension is varied. While working within the dilute limit the viscosity is found to increase linearly with concentration and the intrinsic viscosity of the suspension is found to be 8000. This anomalously high intrinsic viscosity is compared with the predictions of various models for a rigid cylinder and found to be incompatible with any of the current models. Some suggestions are made as to the way this ODA-SWCNT result may be eventually accommodated within other models.

  19. Impact of lysozyme on stability mechanism of nanozirconia aqueous suspension

    Energy Technology Data Exchange (ETDEWEB)

    Szewczuk-Karpisz, Katarzyna, E-mail: k.szewczuk-karpisz@wp.pl; Wiśniewska, Małgorzata

    2016-08-30

    Highlights: • Adsorption and stabilization-destabilization properties of lysozyme (LSZ) in the nanozirconia-biopolymer solution system were determined. • The stability measurements were performed using turbidimetric method. • Lysozyme macromolecules undergo adsorption on the ZrO{sub 2} surface under electrostatic adsorbent-adsorbate attraction, i.e. at pH 6 and 9. • The biopolymer adsorption impact on the zirconia stability varies at different pH values. - Abstract: The effect of lysozyme (LSZ) presence on the zirconium(IV) oxide (ZrO{sub 2}) aqueous suspension stability was examined. The applied zirconia contains mesopores (with a diameter about 30 nm) and its mean particle size is about 100 nm. To determine the stability mechanism of ZrO{sub 2} suspension in the biopolymer presence, the adsorption and electrokinetic (surface charge density and zeta potential) measurements were performed in the pH range 3–10. The lysozyme adsorption on the nanozirconia surface proceeds mainly through electrostatic forces. Under solid-polymer repulsion conditions, there is no adsorption of lysozyme (pH < 6, C{sub NaCl} 0.01 mol/dm{sup 3}). The increase of solution ionic strength to 0.2 mol/dm{sup 3} causes screening of unfavourable forces and biopolymer adsorption becomes possible. The LSZ addition to the ZrO{sub 2} suspension influences its stability. At pH 3, 4.6 and 7.6, slight improvement of the system stability was obtained. In turn, at pH 9 considerable destabilization of nanozirconia particles covered by polymeric layers occurs.

  20. Measurements on an electromagnetic active suspension system for automotive applications

    NARCIS (Netherlands)

    Gysen, B.L.J.; Paulides, J.J.H.; Lomonova, E.A.; Encica, L.; Gysen, B.L.J.; Jansen, J.W.; Krop, D.C.J.

    2008-01-01

    Abstract—This paper describes the specifications for active suspension systems and provides an electromagnetic solution. Electromagnetic actuation and preliminary control strategies are investigated in order to achieve a suspension system with the ability to absorb road irregularities and perform

  1. Fuzzy logic control of vehicle suspensions with dry friction nonlinearity

    Indian Academy of Sciences (India)

    Fuzzy logic control; active vehicle suspension; suspension space. 1. ... surface unevenness, stability and directional control during handling ..... Burton A W, Truscott A J, Wellstead P E 1995 Analysis, modeling and control of an advanced.

  2. Investigation of sedimentation analysis of suspensions with 20 % of the content halloysite clay

    Directory of Open Access Journals (Sweden)

    A. Z. Issagulov

    2016-04-01

    Full Text Available The paper describes the sedimentation analysis of the suspension. This allows us to get complete information about the particle size distribution used for protection against corrosion of pump parts covered with halloysite, thus giving a complete picture of its properties. Using this method is important in the calculation of concentrations when applied to anticorrosive coating. That in the future will increase the service life of parts on which corrosion liquid with halloysite was applied.

  3. Research on magnetorheological damper suspension with permanent magnet and magnetic valve based on developed FOA-optimal control algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Ping; Gao, Hong [Anhui Polytechnic University, Wuhu (China); Niu, Limin [Anhui University of Technology, Maanshan (China)

    2017-07-15

    Due to the fail safe problem, it was difficult for the existing Magnetorheological damper (MD) to be widely applied in automotive suspensions. Therefore, permanent magnets and magnetic valves were introduced to existing MDs so that fail safe problem could be solved by the magnets and damping force could be adjusted easily by the magnetic valve. Thus, a new Magnetorheological damper with permanent magnet and magnetic valve (MDPMMV) was developed and MDPMMV suspension was studied. First of all, mechanical structure of existing magnetorheological damper applied in automobile suspensions was redesigned, comprising a permanent magnet and a magnetic valve. In addition, prediction model of damping force was built based on electromagnetics theory and Bingham model. Experimental research was onducted on the newly designed damper and goodness of fit between experiment results and simulated ones by models was high. On this basis, a quarter suspension model was built. Then, fruit Fly optimization algorithm (FOA)-optimal control algorithm suitable for automobile suspension was designed based on developing normal FOA. Finally, simulation experiments and bench tests with input surface of pulse road and B road were carried out and the results indicated that working erformance of MDPMMV suspension based on FOA-optimal control algorithm was good.

  4. A first-passage scheme for determination of overall rate constants for non-diffusion-limited suspensions

    Science.gov (United States)

    Lu, Shih-Yuan; Yen, Yi-Ming

    2002-02-01

    A first-passage scheme is devised to determine the overall rate constant of suspensions under the non-diffusion-limited condition. The original first-passage scheme developed for diffusion-limited processes is modified to account for the finite incorporation rate at the inclusion surface by using a concept of the nonzero survival probability of the diffusing entity at entity-inclusion encounters. This nonzero survival probability is obtained from solving a relevant boundary value problem. The new first-passage scheme is validated by an excellent agreement between overall rate constant results from the present development and from an accurate boundary collocation calculation for the three common spherical arrays [J. Chem. Phys. 109, 4985 (1998)], namely simple cubic, body-centered cubic, and face-centered cubic arrays, for a wide range of P and f. Here, P is a dimensionless quantity characterizing the relative rate of diffusion versus surface incorporation, and f is the volume fraction of the inclusion. The scheme is further applied to random spherical suspensions and to investigate the effect of inclusion coagulation on overall rate constants. It is found that randomness in inclusion arrangement tends to lower the overall rate constant for f up to the near close-packing value of the regular arrays because of the inclusion screening effect. This screening effect turns stronger for regular arrays when f is near and above the close-packing value of the regular arrays, and consequently the overall rate constant of the random array exceeds that of the regular array. Inclusion coagulation too induces the inclusion screening effect, and leads to lower overall rate constants.

  5. "Restorative Practices" Offer Alternatives to Suspension

    Science.gov (United States)

    Shah, Nirvi

    2012-01-01

    At City Springs and many other schools across the country, restorative practices are about holding students accountable and getting them to right a wrong. The approach is getting more notice than ever as criticism grows of zero-tolerance disciplinary policies that often require out-of-school suspension and expulsion. Educators are turning to…

  6. Mesoscopic electrohydrodynamic simulations of binary colloidal suspensions

    NARCIS (Netherlands)

    Rivas, Nicolas; Frijters, Stefan; Pagonabarraga, Ignacio; Harting, Jens

    2018-01-01

    A model is presented for the solution of electrokinetic phenomena of colloidal suspensions in fluid mixtures. We solve the discrete Boltzmann equation with a Bhatnagar-Gross-Krook collision operator using the lattice Boltzmann method to simulate binary fluid flows. Solvent-solvent and solvent-solute

  7. 75 FR 68704 - Suspension of Community Eligibility

    Science.gov (United States)

    2010-11-09

    ... DEPARTMENT OF HOMELAND SECURITY Federal Emergency Management Agency 44 CFR Part 64 [Docket ID FEMA-2010-0003; Internal Agency Docket No. FEMA-8155] Suspension of Community Eligibility AGENCY: Federal.... Acadia Parish. Emerg; February 4, 1981, Reg; November 26, 2010, Susp. Iota, Town of, Acadia 220005...

  8. Suspension of Water Droplets on Individual Pillars

    DEFF Research Database (Denmark)

    Tóth, T.; Ferraro, D.; Chiarello, E.

    2011-01-01

    We report results of extensive experimental and numerical studies on the suspension of water drops deposited on cylindrical pillars having circular and square cross sections and different wettabilities. In the case of circular pillars, the drop contact line is pinned to the whole edge contour unt...

  9. ENHANCEMENT OF DURABILITY OF TRACTOR SUSPENSION AXLES

    Directory of Open Access Journals (Sweden)

    I. Doshchechkina

    2017-12-01

    Full Text Available The ‘soft’ nitriding of the suspension axle surface of the T150K tractor at the depth of 0.08 mm enables us to enhance its constructive strength, to increase its service life by 25 % and have a considerable economic effect.

  10. Pair-correlations in swimmer suspensions

    Science.gov (United States)

    Nambiar, Sankalp; Subramanian, Ganesh

    2017-11-01

    Suspensions of rear-actuated swimming microorganisms, such as E.coli, exhibit several interesting phenomena including spontaneous pattern formation above a critical concentration, novel rheological properties, shear-induced concentration banding etc. Explanations based on mean-field theory are only qualitative, since interactions between swimmers are important for typical experimental concentrations. We analytically characterize the hydrodynamic pair-interactions in a quiescent suspension of slender straight swimmers. The pair-correlation, calculated at leading order by integrating the swimmer velocity disturbances along straight trajectories, decays as 1/r2 for r >> L (L being the swimmer size). This allows us to characterize both polar and nematic correlations in an interacting swimmer suspension. In the absence of correlations, the velocity covariance asymptotes from a constant for r > L, the latter being characteristic of a suspension of non-interacting point force-dipoles. On including correlations, the slow decay of the pair-orientation correlation leads to an additional contribution to the velocity covariance that diverges logarithmically with system size.

  11. Baltimore District Tackles High Suspension Rates

    Science.gov (United States)

    Maxwell, Lesli A.

    2007-01-01

    This article reports on how the Baltimore District tackles its high suspension rates. Driven by an increasing belief that zero-tolerance disciplinary policies are ineffective, more educators are embracing strategies that do not exclude misbehaving students from school for offenses such as insubordination, disrespect, cutting class, tardiness, and…

  12. Absorption Spectra of Gold Nanoparticle Suspensions

    Science.gov (United States)

    Anan'eva, M. V.; Nurmukhametov, D. R.; Zverev, A. S.; Nelyubina, N. V.; Zvekov, A. A.; Russakov, D. M.; Kalenskii, A. V.; Eremenko, A. N.

    2018-02-01

    Three gold nanoparticle suspensions are obtained, and mean radii in distributions - (6.1 ± 0.2), (11.9 ± 0.3), and (17.3 ± 0.7) nm - are determined by the transmission electron microscopy method. The optical absorption spectra of suspensions are obtained and studied. Calculation of spectral dependences of the absorption index of suspensions at values of the gold complex refractive index taken from the literature showed a significant deviation of experimental and calculated data in the region of 450-800 nm. Spectral dependences of the absorption of suspensions are simulated within the framework of the Mie-Drude theory taking into account the interband absorption in the form of an additional term in the imaginary part of the dielectric permittivity of the Gaussian type. It is shown that to quantify the spectral dependences in the region of the plasmon absorption band of nanoparticles, correction of the parameters of the interband absorption is necessary in addition to the increase of the relaxation parameter of the Drude theory. Spectral dependences of the dielectric permittivity of gold in nanodimensional state are refined from the solution of the inverse problem. The results of the present work are important for predicting the special features of operation of photonic devices and optical detonators based on gold nanoparticles.

  13. Yield stress of alumina-zirconia suspensions

    International Nuclear Information System (INIS)

    Ramakrishnan, V.; Pradip; Malghan, S.G.

    1996-01-01

    The yield stress of concentrated suspensions of alumina, zirconia, and mixed alumina-zirconia powders was measured by the vane technique as a function of solids loading, relative amounts of alumina and zirconia, and pH. At the isoelectric point (IEP), the yield stress varied as the fourth power of the solids loading. The relative ratio of alumina and zirconia particles was important in determining the yield stress of the suspension at the IEP. The yield stress of single and mixed suspensions showed a marked variation with pH. The maximum value occurred at or near the IEP of the suspension. The effect of electrical double-layer forces on the yield stress can be described on the basis of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. A normalized yield stress--that is, the ratio of the yield stress at a given pH to the yield stress at the IEP predicted by this model--showed good correlation with experimental data

  14. Alternatives to School Disciplinary and Suspension Problems.

    Science.gov (United States)

    South Carolina State Dept. of Education, Columbia. Div. of Instruction.

    Policies and procedures for disciplining students should be designed to teach them responsibility, rather than simply punish them. Providing educational opportunities to behavioral deviants is a problem that does not have a simple solution. However, alternatives to suspension or expulsion must be attempted before these disciplinary actions are…

  15. Applied physics

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    The Physics Division research program that is dedicated primarily to applied research goals involves the interaction of energetic particles with solids. This applied research is carried out in conjunction with the basic research studies from which it evolved

  16. Electrostratic stabilization of suspensions in non-aqueous media

    NARCIS (Netherlands)

    Hoeven, van der P.C.

    1991-01-01

    Concentrated suspensions of detergent powder solids in a liquid nonionic surfactant are considered for practical application as liquid detergent products. If no precautions are taken, upon storage the viscosity of such suspensions increases and the pourability drops because the suspensions are

  17. Preview based control of suspension systems for commercial vehicles

    NARCIS (Netherlands)

    Muijderman, J.H.E.A.; Kok, J.J.; Huisman, R.G.M.; Veldpaus, F.E.; van Heck, J.G.A.M.

    1999-01-01

    An active suspension with preview is developed for the rear axle of a commercial vehicle. The obtained improvements are promising and justify further investigation of the more feasible semi-active suspensions with preview. The inherent non-linearity of semi-active suspensions with switching shock

  18. Professor Jesse W. Beams and the first practical magnetic suspension

    Science.gov (United States)

    Allaire, P. E.; Humphris, R. R.; Lewis, D. W.

    1992-01-01

    Dr. Jesse W. Beams developed the first practical magnetic suspension for high speed rotating devices. The devices included high speed rotating mirrors, ultracentrifuges, and high speed centrifugal field rotors. A brief biography of Dr. Beams is presented, and the following topics are discussed: (1) early axial magnetic suspension for ultracentrifuges; and (2) magnetic suspension for high centrifugal fields.

  19. Fuzzy logic control of vehicle suspensions with dry friction nonlinearity

    Indian Academy of Sciences (India)

    We design and investigate the performance of fuzzy logic-controlled (FLC) active suspensions on a nonlinear vehicle model with four degrees of freedom, without causing any degeneration in suspension working limits. Force actuators were mounted parallel to the suspensions. In this new approach, linear combinations of ...

  20. Behaviour of humic-bentonite aggregates in diluted suspensions ...

    African Journals Online (AJOL)

    Formation and disaggregation of micron-size aggregates in a diluted suspension made up of HSs and bentonite (B) were studied by tracing distribution of aggregate sizes and their counts in freshly prepared and aged suspensions, and at high (10 000) and low (1.0) [HS]/[B] ratios. Diluted HSB suspensions are unstable ...

  1. 15 CFR 2011.207 - Suspension of the certificate system.

    Science.gov (United States)

    2010-01-01

    ..., SYRUPS AND MOLASSES Specialty Sugar § 2011.207 Suspension of the certificate system. (a) Suspension. The.... Notice of such suspension and the effective date thereof shall be published in the Federal Register. (b... such reinstatement and the effective date thereof shall be published in the Federal Register. (c...

  2. 13 CFR 120.660 - Suspension or revocation.

    Science.gov (United States)

    2010-01-01

    ... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Suspension or revocation. 120.660 Section 120.660 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Secondary Market Suspension Or Revocation of Participant in Secondary Market § 120.660 Suspension or revocation. (a...

  3. 39 CFR 3001.114 - Suspension pending review.

    Science.gov (United States)

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Suspension pending review. 3001.114 Section 3001... Suspension pending review. (a) Application. Application for suspension of a determination of the Postal Service to close or consolidate any post office pending the outcome of an appeal to the Postal Regulatory...

  4. 21 CFR 520.905a - Fenbendazole suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Fenbendazole suspension. 520.905a Section 520.905a... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.905a Fenbendazole suspension. (a) Specifications. Each milliliter of suspension contains 100 milligrams (mg) fenbendazole. (b...

  5. Compounding rifampin suspensions with improved injectability for nasogastric enteral feeding tube administration.

    Science.gov (United States)

    de Villiers, Melgardt M; Vogel, Laura; Bogenschutz, Monica C; Fingerhut, Bonnie J; D'Silva, Joseph B; Moore, Anne

    2010-01-01

    Often medications that have to be administered to patients via a nasogastric enteral feeding tubes are only available as tablets and capsules with no suitable commercial liquid alternatives. In such situations, pharmacists and nurses have to compound the tablets and capsule contents into liquid suspension formulations for dosing. The risk of occlusion of the enteral tubes during administration is reduced by employing liquid suspensions that are composed of small and uniform particles, not subject to rapid rates of settling, resistant to caking, and easily and uniformly re-suspended upon agitation. Present techniques often employ a manual process, such as a mortar and pestle, to accomplish the particle size reduction and subsequent incorporation into a suitable liquid diluent. A new compounding device has been invented that employs an automated wet-milling process in a single-use disposable plastic container to compound the suspensions. The two processes were compared using Rifampin capsules and various liquid diluents. A prototype version of the new device was employed in the experiments. The physical characteristics of the compounded suspensions were evaluated by determining sedimentation rate, sedimentation volume, and particle size and shape using laser light scattering, optical microscopy, and scanning electron microscopy techniques. The use characteristic of the compounded suspensions was evaluated using a nasogastric tube inject ability test. The results indicated that suspensions prepared using the new device were more resistant to sedimentation and caking and were easier to re-disperse into a uniform mixture by gentle shaking. The results were a consequence of the particles generated by the new device which were found to be smaller and more uniform in shape and size. The suspensions prepared using the new device did not cause blockage of the enteral feeding tubes in comparison to those prepared using a mortar and pastle. In conclusion, the results indicate

  6. XVIII Mendeleev congress on general and applied chemistry. Summaries of reports in five volumes. Volume 5. IV Russian-French symposium Supramolecular systems in chemistry and biology. II Russian-Indian symposium on organic chemistry. International symposium on present-day radiochemistry Radiochemistry: progress and prospects. International symposium Green chemistry, stable evolution and social responsibility of chemists. Symposium Nucleophilic hydrogen substitution in aromatic systems and related reactions

    International Nuclear Information System (INIS)

    2007-01-01

    The 5 volume of the XVIII Mendeleev congress on general and applied chemistry includes summaries of reports on the subjects of sypramolecular systems in chemistry and biology, organic chemistry, modern radiochemistry, green chemistry - development and social responsibility of chemists, nucleophilic hydrogen substitution in aromatic systems and related chemical reactions [ru

  7. Ecoulement et mise en structure de suspensions macroscopiques

    Science.gov (United States)

    Petit, L.

    In this review, we report the various experimental studies performed on suspensions of solid particules in liquids, and concerning the rheological behaviour of such systems and the ordering of particules under the applied velocity fields. The number of materials which are flowing suspensions (reagents in chemical engineering, paints while spreading, blood flow, muds in oil reservoir) gave rise to a number of experimental studies, especially in the last twenty years. The results show a wide variety of behaviour, even for systems of intermediate concentration. In addition, even for identical systems, the results depend of the type of flow. Then, it is clear that, in addition of the standard parameters which are to be taken into account, it is necessary to consider the type of flow the suspension is submitted to. The flow influences the spatial distribution of the particules, leading to their ordering or migration. These ordering or motions influence the flow, and then, the rheological behaviour of the whole system. So, there is a feedback mechanism from the ordering to the flow, which explains the experimental observations. Nous reportons dans cette revue les différentes études expérimentales réalisées sur les suspensions de particules solides dans un liquide et qui concernent le comportement rhéologique de ces systèmes ainsi que les mouvements des particules sous l'effet des champs de vitesse imposés. Ces mouvements peuvent conduire soit à des mises en structure, ou encore à des migrations des particules. L'importance du nombre de matériaux qui se présentent sous forme de suspension et qui sont mis en écoulement (réactif en génie chimique, peintures lors de leur mise en place, écoulement sanguin, boues dans les forages pétroliers,...) a motivé un grand nombre de travaux expérimentaux plus fondamentaux sur le sujet, particulièrement dans les vingt dernières années. Les résultats correspondants montrent une très grande diversité des

  8. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    International Nuclear Information System (INIS)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop; Kim, Young Hun; Choi, Kyung Hee

    2011-01-01

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers

  9. Effect of Chemical Stabilizers in Silver Nanoparticle Suspensions on Nanotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Eun Joo; Park, Hee Jin; Park, Jun Su; Yoon, Je Yong; Yi, Jong Heop [Seoul National University, Seoul (Korea, Republic of); Kim, Young Hun [Kwangwoon University, Seoul (Korea, Republic of); Choi, Kyung Hee [National Institute of Environmental Research, Incheon (Korea, Republic of)

    2011-02-15

    Colloidal silver nanoparticles (AgNPs) have been commercialized as the typically stabilized form via the addition of a variety of surfactants or polymers. Herein, to examine the effects of stabilizing AgNPs in suspension, we modified the surface of bare AgNPs with four type of surfactants (NaDDBS, SDS, TW80, CTAB) and polymers (PVP, PAA, PAH, CMC). The modified AgNPs was applied to compare suspension stability and nanotoxicity test using Escherichia coli (E. coli) as a model organism. Modification of AgNPs surface using chemical stabilizer may be not related with molecular weight, but chemical structure such as ionic state and functional group of stabilizer. In this study, it is noteworthy that AgNPs modified with a cationic stabilizer (CTAB, PAH) were importantly toxic to E. coli, rather than anionic stabilizers (NaDDBS, SDS). Comparing similar anionic stabilizer, i.e., NaDDBS and SDS, the result showed that lipophilicity of chemical structure can affect on E. coli, because NaDDBS, which contains a lipophilic benzene ring, accelerated the cytotoxicity of AgNPs. Interestingly, none of the stabilizers tested, including biocompatible nonionic stabilizers (i.e., TW80 and cellulose) caused a reduction in AgNP toxicity. This showed that toxicity of AgNPs cannot be reduced using stabilizers.

  10. CFD simulation of solids suspension in stirred tanks: Review

    Directory of Open Access Journals (Sweden)

    Ochieng Aoyi

    2010-01-01

    Full Text Available Many chemical reactions are carried out using stirred tanks, and the efficiency of such systems depends on the quality of mixing, which has been a subject of research for many years. For solid-liquid mixing, traditionally the research efforts were geared towards determining mixing features such as off-bottom solid suspension using experimental techniques. In a few studies that focused on the determination of solids concentration distribution, some methods that have been used have not been accurate enough to account for some small scale flow mal-distribution such as the existence of dead zones. The present review shows that computational fluid dynamic (CFD techniques can be used to simulate mixing features such as solids off-bottom suspension, solids concentration and particle size distribution and cloud height. Information on the effects of particle size and particle size distribution on the solids concentration distribution is still scarce. Advancement of the CFD modeling is towards coupling the physical and kinetic data to capture mixing and reaction at meso- and micro-scales. Solids residence time distribution is important for the design; however, the current CFD models do not predict this parameter. Some advances have been made in recent years to apply CFD simulation to systems that involve fermentation and anaerobic processes. In these systems, complex interaction between the biochemical process and the hydrodynamics is still not well understood. This is one of the areas that still need more attention.

  11. The Effect of Polymer Content on the Non-Newtonian Behavior of Acetaminophen Suspension

    Directory of Open Access Journals (Sweden)

    Eskandar Moghimipour

    2013-01-01

    Full Text Available Acetaminophen is used as an analgesic and antipyretic agent. The aim of the study was evaluation of the effect of different polymers on rheological behavior of acetaminophen suspension. In order to achieve controlled flocculation, sodium chloride was added. Then structural vehicles such as carboxymethyl cellulose (CMC, polyvinyl pyrrolidone (PVP, tragacanth, and magnesium aluminum silicate (Veegum were evaluated individually and in combination. Physical stability parameters such as sedimentation volume (F, redispersibility (n, and growth of crystals of the suspensions were determined. Also, the rheological properties of formulations were studied. The results of this study showed that the combination of suspending agents had the most physical stability and pseudoplastic behavior with some degree of thixotropy. Viscosity of suspensions was increased by adding NaCl 0.02%. Presence of PVP is necessary for improving rheological behavior of suspensions by NaCl. This may be related to the cross-linking between the carbonyl group in the PVP segment and Na+ ions.

  12. Predicting the viscosity of digesta from the physical characteristics of particle suspensions using existing rheological models.

    Science.gov (United States)

    Hardacre, Allan K; Lentle, Roger G; Yap, Sia-Yen; Monro, John A

    2018-05-01

    The measurement of the viscosity of digesta is complicated by settling and compositional changes that accompany digestion. The current work determined whether the apparent and relative viscosities ( η a and η r ) of digesta could be accurately determined from the actual and maximum solid volume fractions ( ϕ and ϕ max , respectively) using the Maron-Pierce equation. The rheological properties of digesta from the small intestine of six pigs were determined at a shear rate of 1 s -1 at 37°C. A series of suspensions of plant fibre in a Newtonian liquid (70% aqueous fructose) were made at viscosities similar to pig digesta by adjusting ϕ The relationships between the apparent and relative viscosities ( η a and η r ) and the plant fibre properties; aspect ratio (AR) and ϕ and ϕ max were then determined for digesta and the suspensions. The ARs for the digesta and plant fibre particles were determined using image analysis of scanning electron micrographs and η a from rheometric flow curves at 37°C, ϕ from image analysis and gas pycnometry, and ϕ max from AR and suspension viscosity. The η r of pig digesta and the test suspensions calculated using the Maron-Pierce equation were, with the exception of two outliers, in proportion with η a determined using a rheometer, indicating that η r could be successfully predicted from the Maron-Pierce equation. © 2018 The Author(s).

  13. Enabling high-rate electrochemical flow capacitors based on mesoporous carbon microspheres suspension electrodes

    Science.gov (United States)

    Tian, Meng; Sun, Yueqing; Zhang, Chuanfang (John); Wang, Jitong; Qiao, Wenming; Ling, Licheng; Long, Donghui

    2017-10-01

    Electrochemical flow capacitor (EFC) is a promising technology for grid energy storage, which combines the fast charging/discharging capability of supercapacitors with the scalable energy capacity of flow batteries. In this study, we report a high-power-density EFC using mesoporous carbon microspheres (MCMs) as suspension electrodes. By using a simple yet effective spray-drying technique, monodispersed MCMs with average particle size of 5 μm, high BET surface area of 1150-1267 m2 g-1, large pore volume of 2-4 cm3 g-1 and controllable mesopore size of 7-30 nm have been successfully prepared. The resultant MCMs suspension electrode shows excellent stability and considerable high capacitance of 100 F g-1 and good cycling ability (86% of initial capacitance after 10000 cycles). Specially, the suspension electrode exhibits excellent rate performance with 75% capacitance retention from 2 to 100 mV s-1, significantly higher than that of microporous carbon electrodes (20∼30%), due to the developed mesoporous channels facilitating for rapid ion diffusion. In addition, the electrochemical responses on both negative and positive suspension electrodes are studied, based on which an optimal capacitance matching between them is suggested for large-scale EFC unit.

  14. Effect of polyvinylpyrrolidone and sodium lauroyl isethionate on kaolinite suspension in an aqueous phase.

    Science.gov (United States)

    Kwan, Chang-Chin; Chu, Wen-Hweu; Shimabayashi, Saburo

    2006-08-01

    Suspension of concentrated kaolinite (20 g/30 ml-medium) in the presence of polyvinylpyrrolidone (PVP) and sodium lauroyl isethionate (SLI) was allowed to evaluate its degree of dispersion based on their rheological studies. Flow curves at low shear rate, measured by means of cone-plate method, showed a non-Newtonian flow. Plastic viscosity and Bingham yield value were derived from the flow curves. Relative viscosity, effective volume fraction and void fraction of secondary particle were also obtained. Results of dispersity and fluidity of the suspension were explained. PVP acted as a flocculant at a concentration lower than 0.1% but as a dispersant at a higher concentration. The presence of SLI could decrease both the Bingham yield value and suspension viscosity. Cooperative and competitive effects of PVP and SLI were found. Results indicated that SLI enhanced the degree of dispersion of kaolinite when PVP was less than 0.1%. The suspension, however, showed a maximum flocculation (i.e., aggregation) at 4 mM SLI when the concentration of PVP was higher than 0.1%.

  15. A nonlinear effective thermal conductivity model for carbon nanotube and nanofiber suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Koo, J; Kang, Y [Department of Mechanical Engineering Kyung Hee University, 1, Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of); Kleinstreuer, C [Department of Mechanical and Aerospace Engineering, North Carolina State University, Campus Box 7910, 3211 Broughton Hall, Raleigh, NC 27695-7910 (United States)], E-mail: jmkoo@khu.ac.kr

    2008-09-17

    It has been experimentally demonstrated that suspensions of carbon nanotubes (CNTs) and nanofibers (CNFs) significantly increase the thermal conductivity of nanofluids; however, a physically sound theory of the underlying phenomenon is still missing. In this study, the nonlinear nature of the effective thermal conductivity enhancement with the particle concentration of CNT and CNF nanofluids is explained physically using the excluded volume concept. Specifically, the number of contacting CNTs and CNFs could be calculated by using the excluded volume concept, where the distance for heat to travel in a cylinder between the contacting cylinders in the thermal network of percolating CNTs and CNFs increased with the excluded volume. In contrast to the effective thermal conductivity model of Sastry et al (2008 Nanotechnology 19 055704) the present revised model could reproduce the nonlinear increase of the thermal conductivity with particle concentration, as well as the dependence on the diameter and aspect ratio of the CNTs and CNFs. It was found that the alignment of CNTs and CNFs due to the long range repulsion force decreases the excluded volume, leading to both the convex and concave nonlinear as well as linear increase of the thermal conductivity with particle concentration. The difference between various carrier fluids of the suspensions could be explained as the result of the change in the excluded volume in different base fluids.

  16. Functional changes in CSF volume estimated using measurement of water T2 relaxation

    NARCIS (Netherlands)

    Piechnik, S.K.; Evans, J.; Bary, L.H.; Wise, R.G.; Jezzard, P.

    2009-01-01

    Cerebrospinal fluid (CSF) provides hydraulic suspension for the brain. The general concept of bulk CSF production, circulation, and reabsorption is well established, but the mechanisms of momentary CSF volume variation corresponding to vasoreactive changes are far less understood. Nine individuals

  17. Takagi-Sugeno Fuzzy Model of a One-Half Semiactive Vehicle Suspension: Lateral Approach

    Directory of Open Access Journals (Sweden)

    L. C. Félix-Herrán

    2015-01-01

    Full Text Available This work presents a novel semiactive model of a one-half lateral vehicle suspension. The contribution of this research is the inclusion of actuator dynamics (two magnetorheological nonlinear dampers in the modelling, which means that more realistic outcomes will be obtained, because, in real life, actuators have physical limitations. Takagi-Sugeno (T-S fuzzy approach is applied to a four-degree-of-freedom (4-DOF lateral one-half vehicle suspension. The system has two magnetorheological (MR dampers, whose numerical values come from a real characterization. T-S allows handling suspension’s components and actuator’s nonlinearities (hysteresis, saturation, and viscoplasticity by means of a set of linear subsystems interconnected via fuzzy membership functions. Due to their linearity, each subsystem can be handled with the very well-known control theory, for example, stability and performance indexes (this is an advantage of the T-S approach. To the best of authors’ knowledge, reported work does not include the aforementioned nonlinearities in the modelling. The generated model is validated via a case of study with simulation results. This research is paramount because it introduces a more accurate (the actuator dynamics, a complex nonlinear subsystem model that could be applied to one-half vehicle suspension control purposes. Suspension systems are extremely important for passenger comfort and stability in ground vehicles.

  18. Viscous properties of aluminum oxide nanotubes and aluminium oxide nanoparticles - silicone oil suspensions

    Science.gov (United States)

    Thapa, Ram; French, Steven; Delgado, Adrian; Ramos, Carlos; Gutierrez, Jose; Chipara, Mircea; Lozano, Karen

    2010-03-01

    Electrorheological (ER) fluids consisting of γ-aluminum oxide nanotubes and γ-aluminum oxide nanoparticles dispersed within silicone oil were prepared. The relationship between shear stress and shear rate was measured and theoretically simulated by using an extended Bingham model for both the rheological and electrorheological features of these systems. Shear stress and viscosity showed a sharp increase for the aluminum oxide nanotubes suspensions subjected to applied electric fields whereas aluminum oxide nanoparticles suspensions showed a moderate change. It was found that the transition from liquid to solid state (mediated by the applied electric field) can be described by a power law and that for low applied voltages the relationship is almost linear.

  19. Reflection coefficients of permeant molecules in human red cell suspensions.

    Science.gov (United States)

    Owen, J D; Eyring, E M

    1975-08-01

    The Staverman reflection coefficient, sigma for several permeant molecules was determined in human red cell suspensions with a Durrum stopped-flow spectrophotometer. This procedure was first used with dog, cat, and beef red cells and with human red cells. The stopped-flow technique used was similar to the rapid-flow method used by those who originally reported sigma measurements in human red cells for molecules which rapidly penetrate the red cell membrane. The sigma values we obtained agreed with those previously reported for most of the slow penetrants, except malonamide, but disagreed with all the sigma values previously reported for the rapid penetrants. We were unable to calculate an "equivalent pore radius" with our sigma data. The advantages of our equipment and our experimental procedure are discussed. Our sigma data suggest that sigma is indirectly proportional to the log of the nonelectrolyte permeability coefficient, omega. Since a similar trend has been previously shown for log omega and molar volume of the permeant molecules, a correlatioo was shown between sigma and molar volume suggesting the membrane acts as a sieve.

  20. Study on kinematic and compliance test of suspension

    Science.gov (United States)

    Jing, Lixin; Wu, Liguang; Li, Xuepeng; Zhang, Yu

    2017-09-01

    Chassis performance development is a major difficulty in vehicle research and development, which is the main factor restricting the independent development of vehicles in China. These years, through a large number of studies, chassis engineers have found that the suspension K&C characteristics as a quasi-static characteristic of the suspension provides a technical route for the suspension performance R&D, and the suspension K&C test has become an important means of vehicle benchmarking, optimization and verification. However, the research on suspension K&C test is less in china, and the test conditions and setting requirements vary greatly from OEM to OEM. In this paper, the influence of different settings on the characteristics of the suspension is obtained through experiments, and the causes of the differences are analyzed; in order to fully reflect the suspension characteristics, the author recommends the appropriate test case and settings.

  1. System and technique for ultrasonic characterization of settling suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Greenwood, Margaret S [Richland, WA; Panetta, Paul D [Richland, WA; Bamberger, Judith A [Richland, WA; Pappas, Richard A [Richland, WA

    2006-11-28

    A system for determining properties of settling suspensions includes a settling container, a mixer, and devices for ultrasonic interrogation transverse to the settling direction. A computer system controls operation of the mixer and the interrogation devices and records the response to the interrogating as a function of settling time, which is then used to determine suspension properties. Attenuation versus settling time for dilute suspensions, such as dilute wood pulp suspension, exhibits a peak at different settling times for suspensions having different properties, and the location of this peak is used as one mechanism for characterizing suspensions. Alternatively or in addition, a plurality of ultrasound receivers are arranged at different angles to a common transmitter to receive scattering responses at a variety of angles during particle settling. Angular differences in scattering as a function of settling time are also used to characterize the suspension.

  2. Nonlinear Predictive Sliding Mode Control for Active Suspension System

    Directory of Open Access Journals (Sweden)

    Dazhuang Wang

    2018-01-01

    Full Text Available An active suspension system is important in meeting the requirements of the ride comfort and handling stability for vehicles. In this work, a nonlinear model of active suspension system and a corresponding nonlinear robust predictive sliding mode control are established for the control problem of active suspension. Firstly, a seven-degree-of-freedom active suspension model is established considering the nonlinear effects of springs and dampers; and secondly, the dynamic model is expanded in the time domain, and the corresponding predictive sliding mode control is established. The uncertainties in the controller are approximated by the fuzzy logic system, and the adaptive controller reduces the approximation error to increase the robustness of the control system. Finally, the simulation results show that the ride comfort and handling stability performance of the active suspension system is better than that of the passive suspension system and the Skyhook active suspension. Thus, the system can obviously improve the shock absorption performance of vehicles.

  3. Structure and dynamics of soft repulsive colloidal suspensions in the vicinity of the glass transition.

    Science.gov (United States)

    Crassous, Jérôme J; Casal-Dujat, Lucia; Medebach, Martin; Obiols-Rabasa, Marc; Vincent, Romaric; Reinhold, Frank; Boyko, Volodymyr; Willerich, Immanuel; Menzel, Andreas; Moitzi, Christian; Reck, Bernd; Schurtenberger, Peter

    2013-08-20

    We use a combination of different scattering techniques and rheology to highlight the link between structure and dynamics of dense aqueous suspensions of soft repulsive colloids in the vicinity of a glass transition. Three different latex formulations with an increasing amount of the hydrophilic component resulting in either purely electrostatically or electrosterically stabilized suspensions are investigated. From the analysis of the static structure factor measured by small-angle X-ray scattering, we derive an effective volume fraction that includes contributions from interparticle interactions. We further investigate the dynamics of the suspensions using 3D cross-correlation dynamic light scattering (3DDLS) and rheology. We analyze the data using an effective hard sphere model and in particular compare the linear viscoelasticity and flow behavior to the predictions of mode coupling theory, which accounts for a purely kinetic glass transition determined by the equilibrium structure factor. We demonstrate that seemingly very different colloidal systems exhibit the same generic behavior when the effects from interparticle interactions are incorporated using an effective volume fraction description.

  4. Parameters Analysis of Hydraulic-Electrical Energy Regenerative Absorber on Suspension Performance

    Directory of Open Access Journals (Sweden)

    Han Zhang

    2014-05-01

    Full Text Available To recycle the vibration energy of vehicles over rough roads, a hydraulic-electricity energy regenerative suspension (HEERS was designed in the present work, and simulations were performed with focus on its performance. On the basis of the system principle, the mathematical model of hydraulic-electrical energy regenerative absorber (HEERA and two degrees of freedom (DOF suspension dynamic model were constructed. Using the model of HEERA, simulations on force-displacement and force-velocity characteristics were performed with a 1.67 Hz frequency and a sinusoidal input adopted. And then in combination with HEERA model and two DOF suspension models, simulations on the performance of HEERS also were carried out. Finally, the influences of charging pressure and volume of the accumulator, hydraulic motor displacement, orifice area of check valve, and inner diameter of hydraulic pipelines on the performance of HEERA and HEERS were investigated in depth. The simulation results indicated that (i the damping characteristic of HEERA was coincident with the damping characteristics of traditional absorber; (ii the most remarkable influencing factor on the performance of HEERS was the hydraulic motor displacement, followed by orifice area of check valve, inner diameter of pipelines, and charging pressure of accumulator, while the effects of charging volume of accumulator were quite limited.

  5. Segregation and periodic mixing in a fluidized bidisperse suspension

    International Nuclear Information System (INIS)

    Deboeuf, A; Gauthier, G; Martin, J; Salin, D

    2011-01-01

    We address the issue of segregation in bidisperse suspensions of glass beads, by using a liquid fluidized bed in the inertialess regime and an acoustic technique for acquiring the axial composition along the column. Fluidization balances the buoyancy of the particles by a constant uniform upward flow, and therefore enables long-time experiments. From the analysis of the transient segregation fronts, we have collected precise measurements on the sedimentation velocities of small and large beads, U s and U l , in homogeneous suspensions at the same volume fraction, Φ-bar/2, for both the bead species, and for different size ratios, 1.13≤λ≤1.64, and solid concentrations, 25%≤Φ-bar≤50%. Our measurements provide evidence for a difference in the sedimentation velocities, U s and U l , over all the ranges of λ and Φ-bar covered. These results make one expect that a long-term fluidization should then result in a stationary segregated state, which was indeed always obtained for large enough particle size ratios, λ≥1.43. However, at high concentration and for particles of close sizes, λ≤1.41, we observed a surprising pseudo-periodic intermittency of slow segregation and quick mixing phases. The intermittency time is much longer than the batch sedimentation time and becomes noisy at very high concentration, for which metastable states have been observed. The origin of the mixing destabilization remains an open issue, but we note however that the domain of occurrence, λ≤1.41, also corresponds, in our experiments, to a continuous size distribution of the particles.

  6. Simulation of shear thickening in attractive colloidal suspensions.

    Science.gov (United States)

    Pednekar, Sidhant; Chun, Jaehun; Morris, Jeffrey F

    2017-03-01

    The influence of attractive forces between particles under conditions of large particle volume fraction, ϕ, is addressed using numerical simulations which account for hydrodynamic, Brownian, conservative and frictional contact forces. The focus is on conditions for which a significant increase in the apparent viscosity at small shear rates, and possibly the development of a yield stress, is observed. The high shear rate behavior for Brownian suspensions has been shown in recent work [R. Mari, R. Seto, J. F. Morris and M. M. Denn PNAS, 2015, 112, 15326-15330] to be captured by the inclusion of pairwise forces of two forms, one a contact frictional interaction and the second a repulsive force often found in stabilized colloidal dispersions. Under such conditions, shear thickening is observed when shear stress is comparable to the sum of the Brownian stress, kT/a 3 , and a characteristic stress based on the combination of interparticle force, i.e. σ ∼ F 0 /a 2 with kT the thermal energy, F 0 the repulsive force scale and a the particle radius. At sufficiently large ϕ, this shear thickening can be very abrupt. Here it is shown that when attractive interactions are present with the noted forces, the shear thickening is obscured, as the viscosity shear thins with increasing shear rate, eventually descending from an infinite value (yield stress conditions) to a plateau at large stress; this plateau is at the same level as the large-shear rate viscosity found in the shear thickened state without attractive forces. It is shown that this behavior is consistent with prior observations in shear thickening suspensions modified to be attractive through depletion flocculation [V. Gopalakrishnan and C. F. Zukoski J. Rheol., 2004, 48, 1321-1344]. The contributions of the contact, attractive, and hydrodynamics forces to the bulk stress are presented, as are the contact networks found at different attractive strengths.

  7. Reliable fuzzy H∞ control for active suspension of in-wheel motor driven electric vehicles with dynamic damping

    Science.gov (United States)

    Shao, Xinxin; Naghdy, Fazel; Du, Haiping

    2017-03-01

    A fault-tolerant fuzzy H∞ control design approach for active suspension of in-wheel motor driven electric vehicles in the presence of sprung mass variation, actuator faults and control input constraints is proposed. The controller is designed based on the quarter-car active suspension model with a dynamic-damping-in-wheel-motor-driven-system, in which the suspended motor is operated as a dynamic absorber. The Takagi-Sugeno (T-S) fuzzy model is used to model this suspension with possible sprung mass variation. The parallel-distributed compensation (PDC) scheme is deployed to derive a fault-tolerant fuzzy controller for the T-S fuzzy suspension model. In order to reduce the motor wear caused by the dynamic force transmitted to the in-wheel motor, the dynamic force is taken as an additional controlled output besides the traditional optimization objectives such as sprung mass acceleration, suspension deflection and actuator saturation. The H∞ performance of the proposed controller is derived as linear matrix inequalities (LMIs) comprising three equality constraints which are solved efficiently by means of MATLAB LMI Toolbox. The proposed controller is applied to an electric vehicle suspension and its effectiveness is demonstrated through computer simulation.

  8. In situ characterization of organo-modified and unmodified montmorillonite aqueous suspensions by UV-visible spectroscopy.

    Science.gov (United States)

    Alin, Jonas; Rubino, Maria; Auras, Rafael

    2015-10-15

    UV-visible (UV-Vis) spectroscopy (Tyndall spectra) was applied and tested for its ability to measure organo-modified and unmodified montmorillonite (MMT) clays in aqueous suspensions. A full factorial design of experiments was used to study the influence of pH, NaCl and clay concentrations on the average particle size of the clay agglomerates. The methodology was evaluated by observing results that were consistent with previous research about the unmodified clay's behavior in aqueous suspensions. The results from this evaluation corresponded to accepted theories about the unmodified clay's behavior, indicating that the methodology is precise enough to distinguish the effects of the studied factors on these clay suspensions. The effect of clay concentration was related to the amount of ions per clay particle for the unmodified clay, but was not significant for the organo-modified MMT. The average particle size of the organo-modified MMT in suspension was significantly larger than that of the unmodified clay. Size of the organo-modified MMT agglomerates in suspension decreased in the presence of NaCl and at both high and low pH; this behavior was opposite to that of the unmodified clay. These results demonstrate that the UV-Vis methodology is well-suited for characterizing clay particle size in aqueous suspensions. The technique also is simple, rapid, and low-cost. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Model of heap formation in vibrated gravitational suspensions.

    Science.gov (United States)

    Ebata, Hiroyuki; Sano, Masaki

    2015-11-01

    In vertically vibrated dense suspensions, several localized structures have been discovered, such as heaps, stable holes, expanding holes, and replicating holes. Because an inclined free fluid surface is difficult to maintain because of gravitational pressure, the mechanism of those structures is not understood intuitively. In this paper, as a candidate for the driving mechanism, we focus on the boundary condition on a solid wall: the slip-nonslip switching boundary condition in synchronization with vertical vibration. By applying the lubrication approximation, we derived the time evolution equation of the fluid thickness from the Oldroyd-B fluid model. In our model we show that the initially flat fluid layer becomes unstable in a subcritical manner, and heaps and convectional flow appear. The obtained results are consistent with those observed experimentally. We also find that heaps climb a slope when the bottom is slightly inclined. We show that viscoelasticity enhances heap formation and climbing of a heap on the slope.

  10. Applied Electromagnetics

    Energy Technology Data Exchange (ETDEWEB)

    Yamashita, H; Marinova, I; Cingoski, V [eds.

    2002-07-01

    These proceedings contain papers relating to the 3rd Japanese-Bulgarian-Macedonian Joint Seminar on Applied Electromagnetics. Included are the following groups: Numerical Methods I; Electrical and Mechanical System Analysis and Simulations; Inverse Problems and Optimizations; Software Methodology; Numerical Methods II; Applied Electromagnetics.

  11. Applied Electromagnetics

    International Nuclear Information System (INIS)

    Yamashita, H.; Marinova, I.; Cingoski, V.

    2002-01-01

    These proceedings contain papers relating to the 3rd Japanese-Bulgarian-Macedonian Joint Seminar on Applied Electromagnetics. Included are the following groups: Numerical Methods I; Electrical and Mechanical System Analysis and Simulations; Inverse Problems and Optimizations; Software Methodology; Numerical Methods II; Applied Electromagnetics

  12. Time varying behaviour of the loudspeaker suspension

    DEFF Research Database (Denmark)

    Agerkvist, Finn; Pedersen, Bo Rohde

    2009-01-01

    The compliance of the loudspeaker suspension is known to depend on the recent excitation level history. Previous investigations have shown that the electrical power as well as displacement and velocity plays a role. In this paper the hypothesis that the changes in compliance are caused mainly...... by how much the suspension has been stretched, i.e., the maximum displacement, is investigated. For this purpose the changes in compliance are measured when exposing the loudspeaker to different levels and types of electrical excitation signals, as well as mechanical excitation only. For sinusoidal...... excitation the change in compliance is shown to depend primarily on maximum displacement. But for square pulse excitation the duration of the excitation also plays an important role....

  13. Constraint Embedding for Vehicle Suspension Dynamics

    Directory of Open Access Journals (Sweden)

    Jain Abhinandan

    2016-06-01

    Full Text Available The goal of this research is to achieve close to real-time dynamics performance for allowing auto-pilot in-the-loop testing of unmanned ground vehicles (UGV for urban as well as off-road scenarios. The overall vehicle dynamics performance is governed by the multibody dynamics model for the vehicle, the wheel/terrain interaction dynamics and the onboard control system. The topic of this paper is the development of computationally efficient and accurate dynamics model for ground vehicles with complex suspension dynamics. A challenge is that typical vehicle suspensions involve closed-chain loops which require expensive DAE integration techniques. In this paper, we illustrate the use the alternative constraint embedding technique to reduce the cost and improve the accuracy of the dynamics model for the vehicle.

  14. Mesoscopic electrohydrodynamic simulations of binary colloidal suspensions

    Science.gov (United States)

    Rivas, Nicolas; Frijters, Stefan; Pagonabarraga, Ignacio; Harting, Jens

    2018-04-01

    A model is presented for the solution of electrokinetic phenomena of colloidal suspensions in fluid mixtures. We solve the discrete Boltzmann equation with a Bhatnagar-Gross-Krook collision operator using the lattice Boltzmann method to simulate binary fluid flows. Solvent-solvent and solvent-solute interactions are implemented using a pseudopotential model. The Nernst-Planck equation, describing the kinetics of dissolved ion species, is solved using a finite difference discretization based on the link-flux method. The colloids are resolved on the lattice and coupled to the hydrodynamics and electrokinetics through appropriate boundary conditions. We present the first full integration of these three elements. The model is validated by comparing with known analytic solutions of ionic distributions at fluid interfaces, dielectric droplet deformations, and the electrophoretic mobility of colloidal suspensions. Its possibilities are explored by considering various physical systems, such as breakup of charged and neutral droplets and colloidal dynamics at either planar or spherical fluid interfaces.

  15. Submerged cutting characteristics of abrasive suspension jet

    International Nuclear Information System (INIS)

    Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroyuki

    2015-01-01

    An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth under submerged condition divided by the cutting depth in air at the same standoff distance. The relative cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

  16. Submerged cutting characteristics of abrasive suspension jet

    International Nuclear Information System (INIS)

    Shimizu, Seiji; Peng, Guoyi; Oguma, Yasuyuki; Nishikata, Hiroki

    2015-01-01

    An abrasive suspension jet (ASJ) formed by propelling abrasive suspension through a nozzle has a greater cutting capability than the conventional abrasive water jet. However the cutting capability of submerged ASJs decreases drastically with increasing the standoff distance and the pressure around the jet. A sheathed nozzle nozzle with ventilation for ASJs has been developed as a mean of extending the effective stand-off distance and improving the cutting capabilities under submerged condition. In the present investigation, cutting tests by ASJs in air and under submerged condition are conducted with specimens of aluminum alloy. Air coated ASJs are formed by using a sheathed nozzle with ventilation. The relative cutting depth is defined as the cutting depth is arranged effectually by the cavitation number based on the cavity pressure measured at the sheath. (author)

  17. Compressed Air Production Using Vehicle Suspension

    Directory of Open Access Journals (Sweden)

    Ninad Arun Malpure

    2015-08-01

    Full Text Available Abstract Generally compressed air is produced using different types of air compressors which consumes lot of electric energy and is noisy. In this paper an innovative idea is put forth for production of compressed air using movement of vehicle suspension which normal is wasted. The conversion of the force energy into the compressed air is carried out by the mechanism which consists of the vehicle suspension system hydraulic cylinder Non-return valve air compressor and air receiver. We are collecting air in the cylinder and store this energy into the tank by simply driving the vehicle. This method is non-conventional as no fuel input is required and is least polluting.

  18. Vibration Reduction System Using Magnetic Suspension Technology

    Directory of Open Access Journals (Sweden)

    Spychała Jarosław

    2015-01-01

    Full Text Available The article presents considerations concerning the construction of vibration reduction system using magnetic suspension technology. Presents the results of simulation, numerical and experimental the bearingless electric motor, for which successfully used this type of solution. Positive results of research and testing have become the basis for the development of the concept of building this type of active vibration reduction system , at the same time acting as a support for a technical object, which is a jet engine. Bearing failures are manifested by loss or distortion of their mass, which leads to a total destruction of the roller bearing, and thus reflected in the security. The article presents the concept of building active magnetic suspension to eliminate the bearing system of classical rolling bearing and replace it with magnetic bearing.

  19. Low Reynolds number suspension gravity currents.

    Science.gov (United States)

    Saha, Sandeep; Salin, Dominique; Talon, Laurent

    2013-08-01

    The extension of a gravity current in a lock-exchange problem, proceeds as square root of time in the viscous-buoyancy phase, where there is a balance between gravitational and viscous forces. In the presence of particles however, this scenario is drastically altered, because sedimentation reduces the motive gravitational force and introduces a finite distance and time at which the gravity current halts. We investigate the spreading of low Reynolds number suspension gravity currents using a novel approach based on the Lattice-Boltzmann (LB) method. The suspension is modeled as a continuous medium with a concentration-dependent viscosity. The settling of particles is simulated using a drift flux function approach that enables us to capture sudden discontinuities in particle concentration that travel as kinematic shock waves. Thereafter a numerical investigation of lock-exchange flows between pure fluids of unequal viscosity, reveals the existence of wall layers which reduce the spreading rate substantially compared to the lubrication theory prediction. In suspension gravity currents, we observe that the settling of particles leads to the formation of two additional fronts: a horizontal front near the top that descends vertically and a sediment layer at the bottom which aggrandises due to deposition of particles. Three phases are identified in the spreading process: the final corresponding to the mutual approach of the two horizontal fronts while the laterally advancing front halts indicating that the suspension current stops even before all the particles have settled. The first two regimes represent a constant and a decreasing spreading rate respectively. Finally we conduct experiments to substantiate the conclusions of our numerical and theoretical investigation.

  20. The aqueous homogeneous suspension reactor project

    International Nuclear Information System (INIS)

    1975-01-01

    The power of the KSTR reactor has been increased up to 200 kW in the fourth quarter of 1974. A description is given of the behaviour of the reactor at increased power level, safety aspects concerned with this new level, the operation of the reactor, instrumental behavior and mechanical behavior. Irradiation investigation of two types of fuels are reported and results are presented. Progress made on the conceptual design of a 250 MWe suspension reactor is described

  1. A Model of Active Roll Vehicle Suspension

    Directory of Open Access Journals (Sweden)

    I. Čech

    2010-01-01

    Full Text Available This paper describes active suspension with active roll for four-wheel vehicle (bus by means of an in-series pump actuator with doubled hydropneumatic springs. It also gives full control law with no sky-craping. Lateral stiffness and solid axle geometry in the mechanical model are not neglected. Responses to lateral input as well as responses to statistical unevennesses show considerable improvement of passengers comfort and safety when cornering.

  2. Magnetic suspension - Today's marvel, tomorrow's tool

    Science.gov (United States)

    Lawing, Pierce L.

    1989-01-01

    NASA's Langley facility has through constant advocacy of magnetic suspension systems (MSSs) for wind-tunnel model positioning obtained a technology-development status for the requisite large magnets, computers, automatic control techniques, and apparatus configurations, to contemplate the construction of MSSs for large wind tunnels. Attention is presently given to the prospects for MSSs in wind tunnels employing superfluid helium atmospheres to obtain very high Reynolds numbers, where the MSS can yield substantial enhancements of wind tunnel productivity.

  3. Geometrical analysis of suspension flows near jamming

    Science.gov (United States)

    Wyart, Matthieu

    2012-02-01

    The viscosity of suspensions was computed early on by Einstein and Batchelor in the dilute regime. At high density however, their rheology remains mystifying. As the packing fraction increases, steric hindrance becomes dominant and particles move under stress in a more and more coordinated way. Eventually, the viscosity diverges as the suspension jams into an amorphous solid. Such a jamming transition is reminiscent of critical points: the rheology displays scaling and a diverging length scale. Jamming bear similarities with the glass transition where steric hindrance is enhanced under cooling, and where the dynamics is also observed to become more and more collective as it slows down. In all these examples, understanding the nature of the collective dynamics and the associated rheology remains a challenge. Recent progress has been made however on a related problem, the unjamming transition where a solid made of repulsive soft particles is isotropically decompressed toward vanishing pressure. In this situation various properties of the amorphous solid, such as elasticity, transport or force propagation, display scaling with the distance to threshold. Theoretically these observations can be shown to stem from the presence of soft modes in the vibrational spectrum, a result that can be extended to thermal colloidal glasses as well. Here we focus on particles driven by shear at zero temperature. We show that if hydrodynamical interactions are neglected an analogy can be made between the rheology of such a suspension and the elasticity of simple networks, building a link between the jamming and the unjamming transition. This analogy enables us to unify in a common framework key aspects of the elasticity of amorphous solids with the rheology of dense suspensions, and to relate features of the latter to the geometry of configurations visited under flow.

  4. Torsional asymmetry in suspension bridge systems

    Czech Academy of Sciences Publication Activity Database

    Malík, Josef

    2015-01-01

    Roč. 60, č. 6 (2015), s. 677-701 ISSN 0862-7940 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : suspension bridge * Hamilton principle * vertical and torsional oscillation * uniqueness * existence Subject RIV: BA - General Mathematics Impact factor: 0.507, year: 2015 http://link.springer.com/article/10.1007%2Fs10492-015-0117-3

  5. Compounded Apixaban Suspensions for Enteral Feeding Tubes.

    Science.gov (United States)

    Caraballo, Maria L; Donmez, Seda; Nathan, Kobi; Zhao, Fang

    2017-07-01

    Objective: There is limited information on compounded apixaban formulations for administration via enteral feeding tubes. This study was designed to identify a suitable apixaban suspension formulation that is easy to prepare in a pharmacy setting, is compatible with commonly used feeding tubes, and has a beyond-use date of 7 days. Methods: Apixaban suspensions were prepared from commercially available 5-mg Eliquis tablets. Several vehicles and compounding methods were screened for ease of preparation, dosage accuracy, and tube compatibility. Two tubing types, polyurethane and polyvinyl chloride, with varying lengths and diameters, were included in the study. They were mounted on a peg board during evaluation to mimic the patient body position. A 7-day stability study of the selected formulation was also conducted. Results: Vehicles containing 40% to 60% Ora-Plus in water all exhibited satisfactory flowability through the tubes. The mortar/pestle compounding method was found to produce more accurate and consistent apixaban suspensions than the pill crusher or crushing syringe method. The selected formulation, 0.25 mg/mL apixaban in 50:50 Ora-Plus:water, was compatible with both tubing types, retaining >98% drug in posttube samples. The stability study also confirmed that this formulation was stable physically and chemically over 7 days of storage at room temperature. Conclusions: A suitable apixaban suspension formulation was identified for administration via enteral feeding tubes. The formulation consisted of 0.25 mg/mL apixaban in 50:50 Ora-Plus:water. The stability study results supported a beyond-use date of 7 days at room temperature.

  6. Spectral analysis connected with suspension bridge systems

    Czech Academy of Sciences Publication Activity Database

    Malík, Josef

    2016-01-01

    Roč. 81, č. 1 (2016), s. 42-75 ISSN 0272-4960 R&D Projects: GA MŠk ED2.1.00/03.0082 Institutional support: RVO:68145535 Keywords : suspension bridge * vertical and torsional oscillation * eigenvalue * eigenvector * flutter Subject RIV: JM - Building Engineering Impact factor: 0.945, year: 2016 http://imamat.oxfordjournals.org/content/early/2015/09/16/imamat.hxv027.short?rss=1

  7. Improved understanding of the acoustophoretic focusing of dense suspensions in a microchannel

    Science.gov (United States)

    Karthick, S.; Sen, A. K.

    2017-11-01

    We provide improved understanding of acoustophoretic focusing of a dense suspension (volume fraction φ >10 % ) in a microchannel subjected to an acoustic standing wave using a proposed theoretical model and experiments. The model is based on the theory of interacting continua and utilizes a momentum transport equation for the mixture, continuity equation, and transport equation for the solid phase. The model demonstrates the interplay between acoustic radiation and shear-induced diffusion (SID) forces that is critical in the focusing of dense suspensions. The shear-induced particle migration model of Leighton and Acrivos, coupled with the acoustic radiation force, is employed to simulate the continuum behavior of particles. In the literature, various closures for the diffusion coefficient Dφ* are available for rigid spheres at high concentrations and nonspherical deformable particles [e.g., red blood cells (RBCs)] at low concentrations. Here we propose a closure for Dφ* for dense suspension of RBCs and validate the proposed model with experimental data. While the available closures for Dφ* fail to predict the acoustic focusing of a dense suspension of nonspherical deformable particles like RBCs, the predictions of the proposed model match experimental data within 15%. Both the model and experiments reveal a competition between acoustic radiation and SID forces that gives rise to an equilibrium width w* of a focused stream of particles at some distance Leq* along the flow direction. Using different shear rates, acoustic energy densities, and particle concentrations, we show that the equilibrium width is governed by Péclet number Pe and Strouhal number Stas w*=1.4(PeSt) -0.5 while the length required to obtain the equilibrium-focused width depends on St as Leq*=3.8 /(St)0.6 . The proposed model and correlations would find significance in the design of microchannels for acoustic focusing of dense suspensions such as undiluted blood.

  8. Design of a suspension system and determining suspension parameters of a medium downforce small Formula type car

    Directory of Open Access Journals (Sweden)

    Biswal Sadjyot

    2017-01-01

    Full Text Available The focus of the paper is on designing a suspension system for a medium downforce small Formula type race car. The paper not only focusses on step by step design for a double wishbone type suspension but will also show the use and role of kinematics software in determining the optimized suspension of the car. The paper will also focus on the use of tire data in determining suspension parameters and the design of the double wishbone suspension. Various parameters, their design importance and the process to optimize them according to suspension design goals will be covered. The easiest and best ways to change the suspension parameters to get the best results will also be covered.

  9. Asystole following Reintubation during Suspension Laryngoscopy

    Directory of Open Access Journals (Sweden)

    Sheryl H. Glassman

    2012-01-01

    Full Text Available Transient increase in heart rate and mean arterial pressure commonly occur during manipulation of the airway via direct laryngoscopy. This phenomenon is understood to be due to a sympathetic nervous system reflex causing an increase in plasma catecholamines. Rarely, severe bradycardia and possible asystole can occur following laryngoscopy. One previous report described asystole during suspension laryngoscopy after uneventful direct laryngoscopy. Here we report a case of asystole occurring at the time of reinsertion and cuff inflation of an endotracheal tube in a patient who had been hemodynamically stable during initial direct laryngoscopy and the ensuing suspension laryngoscopy. The asystole was immediately recognized and successful cardiopulmonary resuscitation was performed with the patient returning to baseline sinus rhythm. Cardiac arrest following laryngoscopy is rare. This case highlights the importance of continued vigilance even after the initial manipulations of the airway by both direct laryngoscopy and suspension laryngoscopy are to be performed. Identifying patients who may benefit from premedication with a vagolytic drug may prevent adversity. Preoperative heart rate analysis can identify patients with strong vagal tone.

  10. Core Muscle Activation in Suspension Training Exercises.

    Science.gov (United States)

    Cugliari, Giovanni; Boccia, Gennaro

    2017-02-01

    A quantitative observational laboratory study was conducted to characterize and classify core training exercises executed in a suspension modality on the base of muscle activation. In a prospective single-group repeated measures design, seventeen active male participants performed four suspension exercises typically associated with core training (roll-out, bodysaw, pike and knee-tuck). Surface electromyographic signals were recorded from lower and upper parts of rectus abdominis, external oblique, internal oblique, lower and upper parts of erector spinae muscles using concentric bipolar electrodes. The average rectified values of electromyographic signals were normalized with respect to individual maximum voluntary isometric contraction of each muscle. Roll-out exercise showed the highest activation of rectus abdominis and oblique muscles compared to the other exercises. The rectus abdominis and external oblique reached an activation higher than 60% of the maximal voluntary contraction (or very close to that threshold, 55%) in roll-out and bodysaw exercises. Findings from this study allow the selection of suspension core training exercises on the basis of quantitative information about the activation of muscles of interest. Roll-out and bodysaw exercises can be considered as suitable for strength training of rectus abdominis and external oblique muscles.

  11. A universal suspension test rig for electrohydraulic active and passive automotive suspension system

    Directory of Open Access Journals (Sweden)

    Mahmoud Omar

    2017-12-01

    Full Text Available A fully active electro-hydraulic and passive automotive quarter car suspensions with their experimental test-rigs are designed and implemented. Investigation of the active performance compared against the passive is performed experimentally and numerically utilizing SIMULINK's Simscape library. Both systems are modeled as single-degree-of-freedom in order to simplify the validation process. Economic considerations were considered during the rig's implementation. The rig consists of two identical platforms fixed side by side allowing testing two independent suspensions simultaneously. Position sensors for sprung and unsprung masses on both platforms are installed. The road input is introduced by a cam and a roller follower mechanism driven by 1.12 kW single phase induction motor with speed reduction assembly. The active hydraulic cylinder was the most viable choice due to its high power-to-weight ratio. The active control is of the proportional-integral-differential (PID type. Though this technique is quite simple and not new, yet the emphasis of this paper is the engineering, design and implementation of the experimental setup and controller. A successful validation process is performed. Ride comfort significantly improved with active suspension, as shown by the results; 24.8% sprung mass vibration attenuation is achieved. The details of the developed system with the analytical and experimental results are presented. Keywords: Active suspension, Passive suspension, Servo, Hydraulic, Control, PID

  12. An investigation of flow properties of metal matrix composites suspensions for injection molding

    International Nuclear Information System (INIS)

    Ahmad, F.; Bevis, M.J.

    1997-01-01

    Flow properties of metal matrix composites suspensions have significant effects on the fibre orientation during mould filling. The results presented in this paper relate to the flow properties of aluminium powder and glass fibres compounded into a sacrificial thermoplastics binder. For this purpose, a range of aluminium compounds and aluminium composite suspensions were investigated over a wide shear rate range expected to occur during injection mould process. Aluminium composites wee prepared by substituting glass fibres for aluminium in aluminium compound. Aluminium composite containing a maximum critical volume fraction of fibres which did not exhibit an increase n viscosity was determined. The effect of temperature on the flow behaviour of aluminium composite was also investigated. (author)

  13. Optimization of Casting Design Parameters on Fabrication of Reliable Semi-Solid Aluminum Suspension Control Arm

    Science.gov (United States)

    Ragab, Kh. A.; Bouaicha, A.; Bouazara, M.

    2017-09-01

    The semi-solid casting process has the advantage of providing reliable mechanical aluminum parts that work continuously in dynamic as control arm of the suspension system in automotive vehicles. The quality performance of dynamic control arm is related to casting mold and gating system designs that affect the fluidity of semi-solid metal during filling the mold. Therefore, this study focuses on improvement in mechanical performance, depending on material characterization, and casting design optimization, of suspension control arms made of A357 aluminum semi-solid alloys. Mechanical and design analyses, applied on the suspension arm, showed the occurrence of mechanical failures at unexpected weak points. Metallurgical analysis showed that the main reason lies in the difficult flow of semi-solid paste through the thin thicknesses of a complex geometry. A design modification procedure is applied to the geometry of the suspension arm to avoid this problem and to improve its quality performance. The design modification of parts was carried out by using SolidWorks design software, evaluation of constraints with ABAQUS, and simulation of flow with ProCast software. The proposed designs showed that the modified suspension arm, without ribs and with a central canvas designed as Z, is considered as a perfect casting design showing an increase in the structural strength of the component. In this case, maximum von Mises stress is 199 MPa that is below the yield strength of the material. The modified casting mold design shows a high uniformity and minim turbulence of molten metal flow during semi-solid casting process.

  14. Influence of flocculating agents and structural vehicles on the physical stability and rheological behavior of nitrofurantoin suspension.

    Science.gov (United States)

    Moghimipour, Eskandar; Salimi, Anayatollah; Rezaee, Saeed; Balack, Maryam; Handali, Somayeh

    2014-05-01

    Nitrofurantoin is a nitrofuran antibiotic that has been used for treatment of urinary tract against positive and negative bacteria. The aim of this study was to evaluate the effect of structural vehicles and flocculating agents on physical stability and rheological behavior of nitrofurantoin suspension. To formulate the suspensions, the effect of glycerin and polysorbate 80 as wetting agents was evaluated and their particle sizes were determined using the sieve method. Then to achieve controlled flocculation, sodium citrate and aluminum chloride were added. After choosing the suitable wetting and flocculating agents, structural vehicles such as sodium carboxyl methyl cellulose and Veegum were evaluated individually and in combination. In addition, the effect of sorbitol on density of continuous phase and some physical stability parameters such as sedimentation volume, degree of flocculation and ease of redispersion of the suspensions were evaluated. After incorporation of structural vehicles, the rheological properties of formulations were also determined to find their flow behavior. According to the results, glycerin (0.2%) and sodium citrate (0.3%) had the best effect on the suspension stability as wetting and flocculating agents, respectively. Rheological properties of formulations showed pseudoplastic behavior with some degree of thixotropy. In conclusion, the suspension containing Veegum 1%, sodium carboxy methyl cellulose 1%, glycerine 0.2%, sodium citrate 0.3% and sorbitol 20 % was chosen as the most physically stable formulation.

  15. Introduction to applied thermodynamics

    CERN Document Server

    Helsdon, R M; Walker, G E

    1965-01-01

    Introduction to Applied Thermodynamics is an introductory text on applied thermodynamics and covers topics ranging from energy and temperature to reversibility and entropy, the first and second laws of thermodynamics, and the properties of ideal gases. Standard air cycles and the thermodynamic properties of pure substances are also discussed, together with gas compressors, combustion, and psychrometry. This volume is comprised of 16 chapters and begins with an overview of the concept of energy as well as the macroscopic and molecular approaches to thermodynamics. The following chapters focus o

  16. Suspension of oysters reduces the populations of Vibrio parahaemolyticus and Vibrio vulnificus.

    Science.gov (United States)

    Cole, K M; Supan, J; Ramirez, A; Johnson, C N

    2015-09-01

    Vibrio parahaemolyticus (Vp) and Vibrio vulnificus (Vv) are associated with the consumption of raw oysters and cause illnesses ranging from simple gastroenteritis to life-threatening septicaemia. These halophilic bacteria are frequently found in marine and estuarine systems, accumulating within the tissues of a number of aquatic organisms and passing on to humans after consumption, through contaminated water, or via open wounds. As benthic organisms capable of filtering 40 gallons of water per hour, sediment is an important source of potentially pathogenic vibrios in oysters destined for raw consumption. This research used off-bottom oyster culture to reduce vibrio concentrations in oysters. Colony hybridization was used to enumerate Vp and Vv in bottom and suspended oysters. Vv and Vp concentrations were generally lower in oysters suspended off-bottom, and suspension decreased vibrio loads in oysters by an average of 13%. Suspension of oysters reduced vibrio concentrations. This study found that oyster suspension significantly reduced some populations of potentially pathogenic vibrios. These results indicate that oyster suspension could be a viable approach for preharvest treatment to reduce illness in consumers of raw oysters. © 2015 The Society for Applied Microbiology.

  17. Multiobjective Robust Design of the Double Wishbone Suspension System Based on Particle Swarm Optimization

    Directory of Open Access Journals (Sweden)

    Xianfu Cheng

    2014-01-01

    Full Text Available The performance of the suspension system is one of the most important factors in the vehicle design. For the double wishbone suspension system, the conventional deterministic optimization does not consider any deviations of design parameters, so design sensitivity analysis and robust optimization design are proposed. In this study, the design parameters of the robust optimization are the positions of the key points, and the random factors are the uncertainties in manufacturing. A simplified model of the double wishbone suspension is established by software ADAMS. The sensitivity analysis is utilized to determine main design variables. Then, the simulation experiment is arranged and the Latin hypercube design is adopted to find the initial points. The Kriging model is employed for fitting the mean and variance of the quality characteristics according to the simulation results. Further, a particle swarm optimization method based on simple PSO is applied and the tradeoff between the mean and deviation of performance is made to solve the robust optimization problem of the double wishbone suspension system.

  18. Red blood cell (RBC) suspensions in confined microflows: Pressure-flow relationship.

    Science.gov (United States)

    Stauber, Hagit; Waisman, Dan; Korin, Netanel; Sznitman, Josué

    2017-10-01

    Microfluidic-based assays have become increasingly popular to explore microcirculation in vitro. In these experiments, blood is resuspended to a desired haematocrit level in a buffer solution, where frequent choices for preparing RBC suspensions comprise notably Dextran and physiological buffer. Yet, the rational for selecting one buffer versus another is often ill-defined and lacks detailed quantification, including ensuing changes in RBC flow characteristics. Here, we revisit RBC suspensions in microflows and attempt to quantify systematically some of the differences emanating between buffers. We measure bulk flow rate (Q) of RBC suspensions, using PBS- and Dextran-40, as a function of the applied pressure drop (ΔP) for two hematocrits (∼0% and 23%). Two distinct microfluidic designs of varying dimensions are employed: a straight channel larger than and a network array similar to the size of individual RBCs. Using the resulting pressure-flow curves, we extract the equivalent hydrodynamic resistances and estimate the relative viscosities. These efforts are a first step in rigorously quantifying the influence of the 'background' buffer on RBC flows within microfluidic devices and thereby underline the importance of purposefully selecting buffer suspensions for microfluidic in vitro assays. Copyright © 2017. Published by Elsevier Ltd.

  19. Multiobjective Robust Design of the Double Wishbone Suspension System Based on Particle Swarm Optimization

    Science.gov (United States)

    Lin, Yuqun

    2014-01-01

    The performance of the suspension system is one of the most important factors in the vehicle design. For the double wishbone suspension system, the conventional deterministic optimization does not consider any deviations of design parameters, so design sensitivity analysis and robust optimization design are proposed. In this study, the design parameters of the robust optimization are the positions of the key points, and the random factors are the uncertainties in manufacturing. A simplified model of the double wishbone suspension is established by software ADAMS. The sensitivity analysis is utilized to determine main design variables. Then, the simulation experiment is arranged and the Latin hypercube design is adopted to find the initial points. The Kriging model is employed for fitting the mean and variance of the quality characteristics according to the simulation results. Further, a particle swarm optimization method based on simple PSO is applied and the tradeoff between the mean and deviation of performance is made to solve the robust optimization problem of the double wishbone suspension system. PMID:24683334

  20. Multiobjective robust design of the double wishbone suspension system based on particle swarm optimization.

    Science.gov (United States)

    Cheng, Xianfu; Lin, Yuqun

    2014-01-01

    The performance of the suspension system is one of the most important factors in the vehicle design. For the double wishbone suspension system, the conventional deterministic optimization does not consider any deviations of design parameters, so design sensitivity analysis and robust optimization design are proposed. In this study, the design parameters of the robust optimization are the positions of the key points, and the random factors are the uncertainties in manufacturing. A simplified model of the double wishbone suspension is established by software ADAMS. The sensitivity analysis is utilized to determine main design variables. Then, the simulation experiment is arranged and the Latin hypercube design is adopted to find the initial points. The Kriging model is employed for fitting the mean and variance of the quality characteristics according to the simulation results. Further, a particle swarm optimization method based on simple PSO is applied and the tradeoff between the mean and deviation of performance is made to solve the robust optimization problem of the double wishbone suspension system.

  1. Suspension culture of pluripotent stem cells: effect of shear on stem cell fate.

    Science.gov (United States)

    Keller, Kevin C; Rodrigues, Beatriz; zur Nieden, Nicole I

    2014-01-01

    Despite significant promise, the routine usage of suspension cell culture to manufacture stem cell-derived differentiated cells has progressed slowly. Suspension culture is an innovative way of either expanding or differentiating cells and sometimes both are combined into a single bioprocess. Its advantages over static 2D culturing include a homogeneous and controllable culture environment and producing a large quantity of cells in a fraction of time. This feature makes suspension cell culture ideal for use in stem cell research and eventually ideal in the large-scale production of differentiated cells for regenerative medicine. Because of their tremendous differentiation capacities and unlimited growth properties, pluripotent stem cells (PSCs) in particular are considered potential sources for future cell-replacement therapies. Currently, expansion of PSCs is accomplished in 2D, which only permits a limited amount of cell growth per culture flask before cells need to be passaged. However, before stem cells can be applied clinically, several aspects of their expansion, such as directed growth, but also differentiation, need to be better controlled. This review will summarize recent advantages in suspension culture of PSCs, while at the same time highlighting current challenges.

  2. Nonlinear reset integrator control design: Application to the active suspension control of vehicles

    OpenAIRE

    Acho Zuppa, Leonardo

    2014-01-01

    We present an unexampled reset integrator control design based on the Clegg integrator system. Using an appropriate mathematical model of our Clegg integrator controller, stability proof of the closed-loop system applied to the vibration control problem of a second-order system is shown without invoking hybrid system theory. Furthermore, we illustrate the pplicability of our controller, from the numerical experiment point of view, to the suspension vibration control of vehicles.

  3. Preliminary investigations of design philosophies and features applicable to large magnetic suspension and balance systems

    Science.gov (United States)

    Britcher, C. P.; Fortescue, P. W.; Allcock, G. A.; Goodyer, M. J.

    1979-01-01

    The technology which is required to allow the principles of magnetic suspension and balance systems (MSBS) to be applied to the high Reynolds number transonic testing of aircraft models is examined. A test facility is presented as comprising a pressurized transonic cryogenic wind tunnel, with the MSBS providing full six degree of freedom control. The electro-magnets which are superconducting and fed from quiet, bipolar power supplies are examined. A model control system having some self adaptive characteristics is discussed.

  4. Study on the adsorption and desorption of fertilizer phosphates by the soil suspensions

    International Nuclear Information System (INIS)

    Puspodikoro, S.

    1978-01-01

    The adsorption and desorption of fertilizer phosphate by soil suspensions were studied with the purpose to improve the efficiency of the use of phosphate fertilizer in rice growing countries. Experiments have shown that the applied phosphate fertilizer was quickly adsorbed by the soil and that the bulk of the fertilizer phosphate got bound to the soil complex. These bound fertilizer phosphates could readily be desorbed by flooding of the soil up to a certain amount. (author)

  5. Toward a general psychological model of tension and suspense.

    Science.gov (United States)

    Lehne, Moritz; Koelsch, Stefan

    2015-01-01

    Tension and suspense are powerful emotional experiences that occur in a wide variety of contexts (e.g., in music, film, literature, and everyday life). The omnipresence of tension and suspense suggests that they build on very basic cognitive and affective mechanisms. However, the psychological underpinnings of tension experiences remain largely unexplained, and tension and suspense are rarely discussed from a general, domain-independent perspective. In this paper, we argue that tension experiences in different contexts (e.g., musical tension or suspense in a movie) build on the same underlying psychological processes. We discuss key components of tension experiences and propose a domain-independent model of tension and suspense. According to this model, tension experiences originate from states of conflict, instability, dissonance, or uncertainty that trigger predictive processes directed at future events of emotional significance. We also discuss possible neural mechanisms underlying tension and suspense. The model provides a theoretical framework that can inform future empirical research on tension phenomena.

  6. Applied mathematics

    CERN Document Server

    Logan, J David

    2013-01-01

    Praise for the Third Edition"Future mathematicians, scientists, and engineers should find the book to be an excellent introductory text for coursework or self-study as well as worth its shelf space for reference." -MAA Reviews Applied Mathematics, Fourth Edition is a thoroughly updated and revised edition on the applications of modeling and analyzing natural, social, and technological processes. The book covers a wide range of key topics in mathematical methods and modeling and highlights the connections between mathematics and the applied and nat

  7. Manipulation of nano-entities in suspension by electric fields

    Science.gov (United States)

    Fan, Donglei

    Nanoscale entities, including nanospheres, nanodisks, nanorings, nanowires and nanotubes are potential building blocks for nanoscale devices. Among them, nanowires is an important type of nanoparticles, due to the potential application in microelectronics and bio-diagnosis. Manipulation of nanowires in suspension has been a formidable problem. As described in this thesis, using AC electric fields applied to strategically designed microelectrodes, nanowires in suspension can be driven to align, to chain, to accelerate in directions parallel and perpendicular to its orientation, to concentrate onto designated places, and to disperse in a controlled manner with high efficiency despite an extremely low Reynolds number at the level of 10-5. Randomly oriented nanowires in suspension can be rapidly assembled into extended nonlinear structures within seconds. We show that both the electric field and its gradient play the essential roles of aligning and transporting the nanowires into scaffolds according to the electric field distributions inherent to the geometry of the microelectrodes. The assembling efficiency depends strongly on the frequency of the applied AC voltages and varies as square of the voltage. Furthermore, nanowires have been rotated by AC electric fields applied to strategically designed electrodes. The rotation of the nanowires can be instantly switched on or off with precisely controlled rotation speed (to at least 25000 rpm), definite chirality, and total angle of rotation. This new method has been used to controllably rotate magnetic and non-magnetic nanowires as well as multi-wall carbon nanotubes. We have also produced a micromotor using a rotating nanowire that can drive particles into circular motion. This has application to microfluidic devices, micro-stirrers, and micro electromechanical systems (MEMS). To move and place nanowires onto designated locations with high precision, electrophoretic force has been combined with dielectrophoretic force to

  8. XIX Mendeleev Congress on general and applied chemistry. Abstract book in 4 volumes. Volume 4. Chemistry aspects of modern energy and alternative energy resources. Chemistry of fossil and renewable hydrocarbon raw materials. Analytical chemistry: novel methods and devices for chemical research and analysis. Chemical education

    International Nuclear Information System (INIS)

    2011-01-01

    The abstracts of the XIX Mendeleev Congress on general and applied chemistry held 25-30 September 2011 in Volgograd are presented. The program includes the Congress plenary and section reports, poster presentations, symposia and round tables on key areas of chemical science and technology, and chemical education. The work of the Congress was held the following sections: 1. Fundamental problems of chemical sciences; 2. Chemistry and technology of materials, including nanomaterials; 3. Physicochemical basis of metallurgical processes; 4. Current issues of chemical production, technical risk assessment; 5. Chemical aspects of modern power and alternative energy sources; 6. Chemistry of fossil and renewable hydrocarbons; 7. Analytical chemistry: new methods and instruments for chemical research and analysis; 8. Chemical education. Volume 4 includes abstracts of oral and poster presentations and presentations of correspondent participants of the sections: Chemistry aspects of modern energy and alternative energy resources; Chemistry of fossil and renewable hydrocarbon raw materials; Analytical chemistry: novel methods and devices for chemical research and analysis; Chemical education, and author index [ru

  9. Applied Enzymology.

    Science.gov (United States)

    Manoharan, Asha; Dreisbach, Joseph H.

    1988-01-01

    Describes some examples of chemical and industrial applications of enzymes. Includes a background, a discussion of structure and reactivity, enzymes as therapeutic agents, enzyme replacement, enzymes used in diagnosis, industrial applications of enzymes, and immobilizing enzymes. Concludes that applied enzymology is an important factor in…

  10. Neural control of magnetic suspension systems

    Science.gov (United States)

    Gray, W. Steven

    1993-01-01

    The purpose of this research program is to design, build and test (in cooperation with NASA personnel from the NASA Langley Research Center) neural controllers for two different small air-gap magnetic suspension systems. The general objective of the program is to study neural network architectures for the purpose of control in an experimental setting and to demonstrate the feasibility of the concept. The specific objectives of the research program are: (1) to demonstrate through simulation and experimentation the feasibility of using neural controllers to stabilize a nonlinear magnetic suspension system; (2) to investigate through simulation and experimentation the performance of neural controllers designs under various types of parametric and nonparametric uncertainty; (3) to investigate through simulation and experimentation various types of neural architectures for real-time control with respect to performance and complexity; and (4) to benchmark in an experimental setting the performance of neural controllers against other types of existing linear and nonlinear compensator designs. To date, the first one-dimensional, small air-gap magnetic suspension system has been built, tested and delivered to the NASA Langley Research Center. The device is currently being stabilized with a digital linear phase-lead controller. The neural controller hardware is under construction. Two different neural network paradigms are under consideration, one based on hidden layer feedforward networks trained via back propagation and one based on using Gaussian radial basis functions trained by analytical methods related to stability conditions. Some advanced nonlinear control algorithms using feedback linearization and sliding mode control are in simulation studies.

  11. Active Electromechanical Suspension System for Planetary Rovers, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Balcones Technologies, LLC proposes to adapt actively controlled suspension technology developed by The University of Texas at Austin Center for Electromechanics...

  12. Magnetic suspension and guidance of high speed vehicles. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Alston, I A; Clark, J M; Hayden, J T

    1972-12-01

    Technical and economical assessments of magnetic suspensions for high speed vehicles and transport systems are reported. In these suspensions the suspending magnet takes the form of a powerful superconducting electromagnet that induces currents while it moves over conducting sheets or loops. A number of vehicle track designs are evaluated for operating cost effectiveness. It is shown that propulsion systems using power collected from the track are more expensive than those using power generated onboard the vehicle, and that the conducting sheet suspension is slightly more expensive than the null flux suspension.

  13. An experimental study and mathematical simulation of adrenergic control of hindlimb vessels in rats after 3-week tail suspension

    DEFF Research Database (Denmark)

    Rodionov, Ivan M; Timin, Eugeny N; Matchkov, Vladimir

    1999-01-01

    Adrenoreactivity of rat hindlimb vessels was studied in experiments with constant-pressure saline perfusion. An original mathematical model was applied to evaluate the mechanism of changes in vascular tone regulation. A 3-week suspension resulted in decreased responses to sympathetic nerve stimul...

  14. A microsphere suspension model of metamaterial fluids

    Directory of Open Access Journals (Sweden)

    Qian Duan

    2017-05-01

    Full Text Available Drawing an analogy to the liquid phase of natural materials, we theoretically propose a microsphere suspension model to realize a metamaterial fluid with artificial electromagnetic indexes. By immersing high-ε, micrometer-sized dielectric spheres in a low-ε insulating oil, the structured fluid exhibits liquid-like properties from dispersing phase as well as the isotropic negative electromagnetic parameters caused by Mie resonances from dispersed microspheres. The work presented here will benefit the development of structured fluids toward metamaterials.

  15. Conductivity maximum in a charged colloidal suspension

    Energy Technology Data Exchange (ETDEWEB)

    Bastea, S

    2009-01-27

    Molecular dynamics simulations of a charged colloidal suspension in the salt-free regime show that the system exhibits an electrical conductivity maximum as a function of colloid charge. We attribute this behavior to two main competing effects: colloid effective charge saturation due to counterion 'condensation' and diffusion slowdown due to the relaxation effect. In agreement with previous observations, we also find that the effective transported charge is larger than the one determined by the Stern layer and suggest that it corresponds to the boundary fluid layer at the surface of the colloidal particles.

  16. Simulations of magnetorheological suspensions in Poiseuille flow

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, Yannis; Klingenberg, Daniel J. [University of Wisconsin-Madison, Department of Chemical and Biological Engineering, Madison, WI (United States)

    2006-06-15

    Particle-level simulations are conducted to study magnetorheological fluids in plane Poiseuille flow. The importance of the boundary conditions for the particles at the channel walls is examined by considering two extreme cases: no friction and infinite coefficient of friction. The inclusion of friction produces Bingham fluid behavior, as commonly observed experimentally for MR suspensions. Lamellar structures, similar to those reported for electrorheological fluids in shear flow, are observed in the post-yield region for both particle boundary conditions. The formation of these lamellae is accompanied by an increase in the bulk fluid velocity. The slip boundary condition produces higher fluid velocities and thicker lamellar structures. (orig.)

  17. Thermocouple pressure bushing in suspension rod

    International Nuclear Information System (INIS)

    Pasek, J.; Ondreicka, K.

    1975-01-01

    The seal is described of jacket thermocouples located in the pressure reducer in the fuel element suspension rod. The thermocouples are sealed in the pressure reducer with a silicon sealing compound. The sealing compound is compressed between the two reducers with a Bellevile spring and a pressure washer secured in position with a spring. The axial pressure of the inner parts of the reducer on the compound is adjustable by means of a thrust screw. The tightness and alignment of the thermocouples in the pressure reducer is achieved by tightening the thrust screw to the stop of the top reducer and the subsequent setting of the sealing compound. (J.B.)

  18. Intrinsic viscosity of a suspension of cubes

    KAUST Repository

    Mallavajula, Rajesh K.

    2013-11-06

    We report on the viscosity of a dilute suspension of cube-shaped particles. Irrespective of the particle size, size distribution, and surface chemistry, we find empirically that cubes manifest an intrinsic viscosity [η]=3.1±0.2, which is substantially higher than the well-known value for spheres, [η]=2.5. The orientation-dependent intrinsic viscosity of cubic particles is determined theoretically using a finite-element solution of the Stokes equations. For isotropically oriented cubes, these calculations show [η]=3.1, in excellent agreement with our experimental observations. © 2013 American Physical Society.

  19. Effect of suspension characteristics on in-flight particle properties and coating microstructures achieved by suspension plasma spray

    Science.gov (United States)

    Aubignat, E.; Planche, M. P.; Allimant, A.; Billières, D.; Girardot, L.; Bailly, Y.; Montavon, G.

    2014-11-01

    This paper focuses on the influence of suspension properties on the manufacturing of coatings by suspension plasma spraying (SPS). For this purpose, alumina suspensions were formulated with two different liquid phases: water and ethanol. Suspensions were atomized with a twin-fluid nozzle and injected in an atmospheric plasma jet. Suspension injection was optimized thanks to shadowgraphy observations and drop size distribution measurements performed by laser diffraction. In-flight particle velocities were evaluated by particle image velocimetry. In addition, splats were collected on glass substrates, with the same conditions as the ones used during the spray process. Scanning electron microscopy (SEM) and profilometry analyses were then performed to observe the splat morphology and thus to get information on plasma / suspension interactions, such as particle agglomeration. Finally, coatings were manufactured, characterized by SEM and compared to each other.

  20. Drug release from non-aqueous suspensions. II. The release of methylxanthines from paraffin suspensions

    NARCIS (Netherlands)

    Blaey, C.J. de; Fokkens, J.G.

    1984-01-01

    The release of 3 methylxanthines, i.e. caffeine, theobromine and theophylline, from suspensions in liquid paraffin to an aqueous phase was determined in an in vitro apparatus. The release rates were determined as a function of the pH of the aqueous phase. It was proved that the release process was

  1. Simple analytical technique for liquid scintillation counting of environmental carbon-14 using gel suspension method

    International Nuclear Information System (INIS)

    Okai, Tomio; Wakabayashi, Genichiro; Nagao, Kenjiro; Matoba, Masaru; Ohura, Hirotaka; Momoshima, Noriyuki; Kawamura, Hidehisa

    2000-01-01

    A simple analytical technique for liquid scintillation counting of environmental 14 C was developed. Commercially available gelling agent, N-lauroyl-L -glutamic -α,γ-dibutylamide, was used for the gel-formation of the samples (gel suspension method) and for the subsequent liquid scintillation counting of 14 C in the form of CaCO 3 . Our procedure for sample preparation is much simpler than that of the conventional methods and requires no special equipment. Self absorption, stability and reproducibility of gel suspension samples were investigated in order to evaluate the characteristics of the gel suspension method for 14 C activity measurement. The self absorption factor is about 70% and slightly decrease as CaCO 3 weight increase. This is considered to be mainly due to the absorption of β-rays and scintillation light by the CaCO 3 sample itself. No change of the counting rate for the gel suspension sample was observed for more than 2 years after the sample preparation. Four samples were used for checking the reproducibility of the sample preparation method. The same values were obtained for the counting rate of 24 C activity within the counting error. No change of the counting rate was observed for the 're-gelated' sample. These results show that the gel suspension method is appropriate for the 14 C activity measurement by the liquid scintillation counting method and useful for a long-term preservation of the sample for repeated measurement. The above analytical technique was applied to actual environmental samples in Fukuoka prefecture, Japan. Results obtained were comparable with those by other researchers and appear to be reasonable. Therefore, the newly developed technique is useful for the routine monitoring of environmental 14 C. (author)

  2. Momentum balance and stresses in a suspension of spherical particles in a plane Couette flow

    Science.gov (United States)

    Rahmani, Mona; Hammouti, Abdelkader; Wachs, Anthony

    2018-04-01

    Non-Brownian suspension of monodisperse spherical particles, with volume fractions ranging between ϕ = 0.05 and 0.38 and particle Reynolds numbers ranging between Rep = 0.002 and 20, in plane Couette shear flows is investigated using three-dimensional particle-resolved numerical simulations. We examine the effects of volume fraction and particle Reynolds number on the macroscopic and microscopic stresses in the fluid phase. The effective viscosity of the suspension is in a good agreement with the previous empirical and experimental studies. At Rep = 20, however, the effective viscosity increases significantly compared to the lower particle Reynolds number simulations in the Stokes flow regime. Examining the stresses over the depth of the Couette gap reveals that this increase in wall shear stresses at high particle Reynolds numbers is mainly due to the significantly higher particle phase stress contributions. Next, we examine the momentum balance in the fluid and particle phase for different regimes to assess the significance of particle/particle interaction and fluid and particle inertia. At the highest particle Reynolds number and volume fraction, the particle inertia plays a dominant role in the momentum balance and the fluid inertia is non-negligible, while the short-lived contact forces are negligible compared to these effects. For all other regimes, the fluid inertia is negligible, but the particle inertia and contact forces are important in the momentum balance. Reynolds stresses originated from velocity fluctuations do not contribute significantly to the suspension stresses in any of the regimes we have studied, while the reduction in the shear-induced particle rotation can be a reason for higher wall shear stress at Rep = 20. Finally, we study the kinematics of particles, including their velocity fluctuations, rotation, and diffusion over the depth of the Couette gap. The particle diffusion coefficients in the cross flow direction exhibit an abrupt

  3. Hardening of particle/oil/water suspensions due to capillary bridges: Experimental yield stress and theoretical interpretation.

    Science.gov (United States)

    Danov, Krassimir D; Georgiev, Mihail T; Kralchevsky, Peter A; Radulova, Gergana M; Gurkov, Theodor D; Stoyanov, Simeon D; Pelan, Eddie G

    2018-01-01

    Suspensions of colloid particles possess the remarkable property to solidify upon the addition of minimal amount of a second liquid that preferentially wets the particles. The hardening is due to the formation of capillary bridges (pendular rings), which connect the particles. Here, we review works on the mechanical properties of such suspensions and related works on the capillary-bridge force, and present new rheological data for the weakly studied concentration range 30-55 vol% particles. The mechanical strength of the solidified capillary suspensions, characterized by the yield stress Y, is measured at the elastic limit for various volume fractions of the particles and the preferentially wetting liquid. A quantitative theoretical model is developed, which relates Y with the maximum of the capillary-bridge force, projected on the shear plane. A semi-empirical expression for the mean number of capillary bridges per particle is proposed. The model agrees very well with the experimental data and gives a quantitative description of the yield stress, which increases with the rise of interfacial tension and with the volume fractions of particles and capillary bridges, but decreases with the rise of particle radius and contact angle. The quantitative description of capillary force is based on the exact theory and numerical calculation of the capillary bridge profile at various bridge volumes and contact angles. An analytical formula for Y is also derived. The comparison of the theoretical and experimental strain at the elastic limit reveals that the fluidization of the capillary suspension takes place only in a deformation zone of thickness up to several hundred particle diameters, which is adjacent to the rheometer's mobile plate. The reported experimental results refer to water-continuous suspension with hydrophobic particles and oily capillary bridges. The comparison of data for bridges from soybean oil and hexadecane surprisingly indicate that the yield strength is

  4. Applied dynamics

    CERN Document Server

    Schiehlen, Werner

    2014-01-01

    Applied Dynamics is an important branch of engineering mechanics widely applied to mechanical and automotive engineering, aerospace and biomechanics as well as control engineering and mechatronics. The computational methods presented are based on common fundamentals. For this purpose analytical mechanics turns out to be very useful where D’Alembert’s principle in the Lagrangian formulation proves to be most efficient. The method of multibody systems, finite element systems and continuous systems are treated consistently. Thus, students get a much better understanding of dynamical phenomena, and engineers in design and development departments using computer codes may check the results more easily by choosing models of different complexity for vibration and stress analysis.

  5. An Active Seat Controller with Vehicle Suspension Feedforward and Feedback States: An Experimental Study

    Directory of Open Access Journals (Sweden)

    Abdulaziz Alfadhli

    2018-04-01

    Full Text Available Active seat suspensions can be used to reduce the harmful vertical vibration of a vehicle’s seat by applying an external force using a closed loop controller. Many of the controllers found in the literature are difficult to implement practically, because they are based on using unavailable or difficult and costly measurements. This paper presents both simulation and experimental studies of five novel, simple, and cost-effective control strategies to be used for an active seat suspension in order to improve ride comfort at low frequencies below 20 Hz. These strategies use available and measurable feedforward (preview information states from the vehicle secondary suspension, as well as feedback states from the seat suspension, together with gains optimised to minimise the occupant vibration. The gains were optimised using a genetic algorithm (GA, with a fitness function based on the seat effective amplitude transmissibility (SEAT factor. Constraints on the control force and the seat suspension stroke were also included in the optimisation algorithm. Simulation and laboratory experimental tests were carried out to assess the performance of the proposed controllers according to the ISO 2631-1 standard, in both the frequency and time domains with a range of different road profiles. The experimental tests were performed using a multi-axis simulation table (MAST and a physical active seat suspension configured as a hardware-in-loop (HIL simulation with a virtual linear quarter vehicle model (QvM. The results demonstrate that the proposed controllers substantially attenuate the vertical vibration at the driver’s seat compared with both a passive and a proportional-integral-derivative (PID active seat suspension and thus improve ride comfort together with reducing vibration-linked health risks. Moreover, experimental results show that employing both feedforward information and feedback vehicle body and seat acceleration signals in the controller

  6. Adaptive suspension strategy for a double wishbone suspension through camber and toe optimization

    Directory of Open Access Journals (Sweden)

    C. Kavitha

    2018-02-01

    Full Text Available A suspension system is responsible for the safety of vehicle during its manoeuvre. It serves the dual purpose of providing stability to the vehicle while providing a comfortable ride quality to the occupants. Recent trends in suspension system have focused on improving comfort and handling of vehicles while keeping the cost, space and feasibility of manufacturing in the constraint. This paper proposes a method for improving handling characteristics of a vehicle by controlling camber and toe angle using variable length arms in an adaptive manner. In order to study the effect of dynamic characteristics of the suspension system, a simulation study has been done in this work. A quarter car physical model with double wishbone suspension geometry is modelled in SolidWorks. It is then imported and simulated using SimMechanics platform in MATLAB. The output characteristics of the passive system (without variable length arms were validated on MSC ADAMS software. The adaptive system intends to improve vehicle handling characteristics by controlling the camber and toe angles. This is accomplished by two telescopic arms with an actuator which changes the camber and toe angle of the wheel dynamically to deliver best possible traction and manoeuvrability. Two PID controllers are employed to trigger the actuators based on the camber and toe angle from the sensors for reducing the error existing between the actual and desired value. The arms are driven by actuators in a closed loop feedback manner with help of a separate control system. Comparison between active and passive systems is carried out by analysing graphs of various parameters obtained from MATLAB simulation. From the results, it is observed that there is a reduction of 58% in the camber and 96% in toe gain. Hence, the system provides the scope of considerable adaptive strategy in controlling dynamic characteristics of the suspension system.

  7. Applied optics

    International Nuclear Information System (INIS)

    Orszag, A.; Antonetti, A.

    1988-01-01

    The 1988 progress report, of the Applied Optics laboratory, of the (Polytechnic School, France), is presented. The optical fiber activities are focused on the development of an optical gyrometer, containing a resonance cavity. The following domains are included, in the research program: the infrared laser physics, the laser sources, the semiconductor physics, the multiple-photon ionization and the nonlinear optics. Investigations on the biomedical, the biological and biophysical domains are carried out. The published papers and the congress communications are listed [fr

  8. Studies on Rapidly Frozen Suspensions of Yeast Cells by Differential Thermal Analysis and Conductometry

    Science.gov (United States)

    Mazur, Peter

    1963-01-01

    Few, if any, yeast cells survived rapid cooling to -196°C and subsequent slow warming. After rapid freezing, the suspensions absorbed latent heat of fusion between -15° and 0°C during warming, and the relation between the amount of heat absorbed and the concentration of cells was the same as that in equivalent KCl solutions, indicating that frozen suspensions behave thermally like frozen solutions. The amount of heat absorbed was such that more than 80 per cent of the intracellular solution had to be frozen. The conductometric behavior of frozen suspensions showed that cell solutes were still inside the cells and surrounded by an intact cell membrane at the time heat was being absorbed. Two models are consistent with these findings. The first assumes that intracellular freezing has taken place; the second that all freezable water has left the cells and frozen externally. The latter model is ruled out because rapidly cooled cells do not shrink by an amount equal to the volume of water that would have to be withdrawn to prevent internal freezing. PMID:13934216

  9. Effect of particle size on laser-induced breakdown spectroscopy analysis of alumina suspension in liquids

    International Nuclear Information System (INIS)

    Diaz Rosado, José Carlos; L'hermite, Daniel; Levi, Yves

    2012-01-01

    The analysis by Laser Induced Breakdown Spectroscopy (LIBS) was proposed for the detection and the quantification of different elements in water even when the analyte is composed of particles in suspension. We have studied the effect of particle size on the LIBS signal during liquid analysis. In our study we used different particle sizes (from 2 μm to 90 μm) of Al 2 O 3 in suspension in water. The results were compared to the signal obtained in the case of dissolved aluminum. In the case of particles, a linear correlation between the LIBS signal versus concentration was found but a significant decrease in the slope of the calibration curve was found when the particle size increased. Several hypotheses have been tested and only a partial ablation of the particles might explain this decrease in signal intensity. This effect probably does not occur at smaller particle size. We estimated 860 nm/pulse as ablated thickness from the top of the particle. A statistical analysis over all data obtained allowed us to calculate 100 μm as ablated water column depth. - Highlights: ► We have identified a decrease of calibration curve when particle size increases. ► Partial particle ablation has been identified as the origin of this effect. ► The ablation rate on Al 2 O 3 particles in suspension in water has been estimated. ► We can determine the deepness of the interaction volume into the liquid.

  10. Improving the cooling performance of electrical distribution transformer using transformer oil – Based MEPCM suspension

    Directory of Open Access Journals (Sweden)

    Mushtaq Ismael Hasan

    2017-04-01

    Full Text Available In this paper the electrical distribution transformer has been studied numerically and the effect of outside temperature on its cooling performance has been investigated. The temperature range studied covers the hot climate regions. 250 KVA distribution transformer is chosen as a study model. A novel cooling fluid is proposed to improve the cooling performance of this transformer, transformer oil-based microencapsulated phase change materials suspension is used with volume concentration (5–25% as a cooling fluid instead of pure transformer oil. Paraffin wax is used as a phase change material to make the suspension, in addition to the ability of heat absorption due to melting, the paraffin wax considered as a good electrical insulator. Results obtained show that, using of MEPCM suspension instead of pure transformer oil lead to improve the cooling performance of transformer by reducing its temperature and as a consequence increasing its protection against the breakdown. The melting fraction increased with increasing outside temperature up to certain temperature after which the melting fraction reach maximum constant value (MF = 1 which indicate that, the choosing of PCM depend on the environment in which the transformer is used.

  11. Thermal transport phenomena in nanoparticle suspensions

    International Nuclear Information System (INIS)

    Cardellini, Annalisa; Fasano, Matteo; Bozorg Bigdeli, Masoud; Chiavazzo, Eliodoro; Asinari, Pietro

    2016-01-01

    Nanoparticle suspensions in liquids have received great attention, as they may offer an approach to enhance thermophysical properties of base fluids. A good variety of applications in engineering and biomedicine has been investigated with the aim of exploiting the above potential. However, the multiscale nature of nanosuspensions raises several issues in defining a comprehensive modelling framework, incorporating relevant molecular details and much larger scale phenomena, such as particle aggregation and their dynamics. The objectives of the present topical review is to report and discuss the main heat and mass transport phenomena ruling macroscopic behaviour of nanosuspensions, arising from molecular details. Relevant experimental results are included and properly put in the context of recent observations and theoretical studies, which solved long-standing debates about thermophysical properties enhancement. Major transport phenomena are discussed and in-depth analysis is carried out for highlighting the role of geometrical (nanoparticle shape, size, aggregation, concentration), chemical (pH, surfactants, functionalization) and physical parameters (temperature, density). We finally overview several computational techniques available at different scales with the aim of drawing the attention on the need for truly multiscale predictive models. This may help the development of next-generation nanoparticle suspensions and their rational use in thermal applications. (topical review)

  12. Standardisation of magnetic nanoparticles in liquid suspension

    Science.gov (United States)

    Wells, James; Kazakova, Olga; Posth, Oliver; Steinhoff, Uwe; Petronis, Sarunas; Bogart, Lara K.; Southern, Paul; Pankhurst, Quentin; Johansson, Christer

    2017-09-01

    Suspensions of magnetic nanoparticles offer diverse opportunities for technology innovation, spanning a large number of industry sectors from imaging and actuation based applications in biomedicine and biotechnology, through large-scale environmental remediation uses such as water purification, to engineering-based applications such as position-controlled lubricants and soaps. Continuous advances in their manufacture have produced an ever-growing range of products, each with their own unique properties. At the same time, the characterisation of magnetic nanoparticles is often complex, and expert knowledge is needed to correctly interpret the measurement data. In many cases, the stringent requirements of the end-user technologies dictate that magnetic nanoparticle products should be clearly defined, well characterised, consistent and safe; or to put it another way—standardised. The aims of this document are to outline the concepts and terminology necessary for discussion of magnetic nanoparticles, to examine the current state-of-the-art in characterisation methods necessary for the most prominent applications of magnetic nanoparticle suspensions, to suggest a possible structure for the future development of standardisation within the field, and to identify areas and topics which deserve to be the focus of future work items. We discuss potential roadmaps for the future standardisation of this developing industry, and the likely challenges to be encountered along the way.

  13. Energy-harvesting potential of automobile suspension

    Science.gov (United States)

    Múčka, Peter

    2016-12-01

    This study is aimed quantify dissipated power in a damper of automobile suspension to predict energy harvesting potential of a passenger car more accurately. Field measurements of power dissipation in a regenerative damper are still rare. The novelty is in using the broad database of real road profiles, a 9 degrees-of-freedom full-car model with real parameters, and a tyre-enveloping contact model. Results were presented as a function of road surface type, velocity and road roughness characterised by International Roughness Index. Results were calculated for 1600 test sections of a total length about 253.5 km. Root mean square of a dissipated power was calculated from 19 to 46 W for all four suspension dampers and velocity 60 km/h and from 24 to 58 W for velocity 90 km/h. Results were compared for a full-car model with a tyre-enveloping road contact, full-car and quarter-car models with a tyre-road point contact. Mean difference among three models in calculated power was a few per cent.

  14. Standardisation of magnetic nanoparticles in liquid suspension

    International Nuclear Information System (INIS)

    Wells, James; Kazakova, Olga; Posth, Oliver; Steinhoff, Uwe; Petronis, Sarunas; Bogart, Lara K; Southern, Paul; Pankhurst, Quentin; Johansson, Christer

    2017-01-01

    Suspensions of magnetic nanoparticles offer diverse opportunities for technology innovation, spanning a large number of industry sectors from imaging and actuation based applications in biomedicine and biotechnology, through large-scale environmental remediation uses such as water purification, to engineering-based applications such as position-controlled lubricants and soaps. Continuous advances in their manufacture have produced an ever-growing range of products, each with their own unique properties. At the same time, the characterisation of magnetic nanoparticles is often complex, and expert knowledge is needed to correctly interpret the measurement data. In many cases, the stringent requirements of the end-user technologies dictate that magnetic nanoparticle products should be clearly defined, well characterised, consistent and safe; or to put it another way—standardised. The aims of this document are to outline the concepts and terminology necessary for discussion of magnetic nanoparticles, to examine the current state-of-the-art in characterisation methods necessary for the most prominent applications of magnetic nanoparticle suspensions, to suggest a possible structure for the future development of standardisation within the field, and to identify areas and topics which deserve to be the focus of future work items. We discuss potential roadmaps for the future standardisation of this developing industry, and the likely challenges to be encountered along the way. (topical review)

  15. Relating the molecular structure of comb-type superplasticizers to the compression rheology of MgO suspensions

    DEFF Research Database (Denmark)

    Kjeldsen, Ane Mette; Flatt, Rober Johan; Bergström, Lennart

    2006-01-01

    chains. Consolidation experiments, where the volume fraction gradient of particle networks has been determined in response to a centrifugal force field, offer a simple, yet accurate, way of investigating flocculated, partly stabilized and stable suspensions under compression. The compression rheology...... behaviour could be related to the estimated thickness of the adsorbed superplasticizers and a scaling analysis was used to quantitatively assess the importance of the length of the grafted PEO-chains on the magnitude of the inter-particle bond strength....

  16. On the assessment of the productivity of suspension cultures of unicellular green algae at defined light conditions

    Energy Technology Data Exchange (ETDEWEB)

    Seiss, U; Borns, E; Boehm, H

    1985-01-01

    A description is given of the possibility of a comparison of the production between different suspension cultures of microalgae at equal and defined light conditions. For this, a variant of the turbidostat technique is used by which with the acid of a phototransistor and the filter combination of red filter/opal glass filter a chlorophyll-equivalent signal is applied for control. The equal light conditions are compared and set by the preparation of the respective absorption profiles. From this one can derive the mean level of irradiation within the suspension cultures and use it as the reference value for the light conditions. By this technique it is possible to set equal light conditions in suspension cultures independent of the given cell sizes, cell shapes and dry matter contents.

  17. Comparative Evaluation of Antifungal Activity of Piper Betel Leaf Oil, Origanum vulgare Essential Oil and Fluconazole Suspension on Candida albicans − An In Vitro Study

    Directory of Open Access Journals (Sweden)

    Nisha Makkar

    2017-01-01

    Full Text Available Introduction: Oropharyngeal candidiasis is an opportunistic mucosal infection caused by Candida albicans. It usually responds to topical treatments such as clotrimazole troches, topical fluconazole, chlorhexidine mouthwash and nystatin suspension. Piper betel leaf oil and Origanum vulgare essential oil have shown some topical antifungal activity. Aim: To determine and compare the antifungal efficacy of piper betel leaf oil, O. vulgare essential oil and fluconazole suspension against C. albicans. Materials and Methods: The zone of inhibition was measured by the cup–plate diffusion method using 100 μl volume of piper betel leaf oil, O. vulgare essential oil and fluconazole suspension, which were pipetted into the wells of the inoculated Sabouraud’s dextrose agar plates. The zone of inhibition was measured in millimetres using Vernier calliper. Minimum inhibitory concentration (MIC was determined by the broth macro-dilution test by pouring 1 ml of the respective concentrations of the test material to the individual test tubes along with 10 μl of the diluted test organism inoculum. Finally, MIC was calculated using a reflective viewer. Results: The zone of inhibition for O. vulgare essential oil (>40 mm was more than fluconazole suspension (>35 mm. MIC of O. vulgare essential oil, piper betel leaf oil and fluconazole suspension was 1.6%, 0.4% and 0.8%, respectively. Conclusion: O. vulgare essential oil was found to be a more effective antifungal agent than piper betel leaf oil and fluconazole suspension.

  18. Electrochemical study of AISI 304 stainless steel during the exposure at the disinfectant solutions with fungal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Stoica, M.; Bruma, M. [Department of Biochemistry and Technologies, Faculty of Food Science and Engineering, ' ' Dunarea de Jos' ' University of Galati, 111 Domneasca Street, 800201 Galati (Romania); Carac, G. [Department of Chemistry, Faculty of Sciences, ' ' Dunarea de Jos' ' University of Galati, 47 Domneasca Street, 800008 Galati (Romania)

    2010-12-15

    The effect of fungal suspensions on the disinfectant solution (Actisept with sodium dichloroisocyanurate as active substance, which releases 140 ppm active chlorine) and the corrosion behavior of type AISI 304 stainless steel (SS) were evaluated through linear polarization. The work presents a study of biocide Actisept solution as reference solution and the mixed solutions: reference biocide Actisept solution with three fungal suspensions (10 vol%), Aspergillus niger, Candida mycoderma, and Saccharomyces cerevisiae. The fungal suspension has an important influence on the synergistic effect of the SS corrosion in the following order: Saccharomyces cerevisiae > Candida mycoderma > Aspergillus niger. The E{sub corr} values from the mixed solutions decreased with immersion time of the samples. In the case of Aspergillus niger, the corrosion rate was lower than that of any other type of fungal suspension tested, because the arrangement in solutions, the size and composition of Aspergillus niger spores were more favorable to protect the spores of the chemical and the electrical stressing. The results showed that there is a synergistic effect between the active substances from the disinfectant, fungal suspensions and applied potential, thus this effect can be taken into consideration for the hygienic and safety food industry. (Copyright copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  19. 17 CFR 32.11 - Suspension of commodity option transactions.

    Science.gov (United States)

    2010-04-01

    ... 17 Commodity and Securities Exchanges 1 2010-04-01 2010-04-01 false Suspension of commodity option... REGULATION OF COMMODITY OPTION TRANSACTIONS § 32.11 Suspension of commodity option transactions. (a... accept money, securities or property in connection with, the purchase or sale of any commodity option, or...

  20. 15 CFR 14.13 - Debarment and suspension.

    Science.gov (United States)

    2010-01-01

    ... 15 Commerce and Foreign Trade 1 2010-01-01 2010-01-01 false Debarment and suspension. 14.13 Section 14.13 Commerce and Foreign Trade Office of the Secretary of Commerce UNIFORM ADMINISTRATIVE... shall comply with the nonprocurement debarment and suspension common rule implementing E.O.s 12549 and...

  1. 12 CFR 19.244 - Automatic removal, suspension, and debarment.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Automatic removal, suspension, and debarment. 19.244 Section 19.244 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY RULES... Services § 19.244 Automatic removal, suspension, and debarment. (a) An independent public accountant or...

  2. 12 CFR 19.243 - Removal, suspension, or debarment.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 1 2010-01-01 2010-01-01 false Removal, suspension, or debarment. 19.243 Section 19.243 Banks and Banking COMPTROLLER OF THE CURRENCY, DEPARTMENT OF THE TREASURY RULES OF PRACTICE AND PROCEDURE Removal, Suspension, and Debarment of Accountants From Performing Audit Services § 19...

  3. The Evolution of Discipline: Alternative to Suspension Programs.

    Science.gov (United States)

    Streva, Michael A.

    Historically, the chosen method of discipline in United States schools has gone from corporal punishment to an emphasis on suspension. Recently, as principals have become less certain about the extent of their authority to suspend students, many inschool programs have been developed as alternatives to suspension. Among the advantages of such…

  4. In-School Suspension Practices and the Prison Hospital Experience

    Science.gov (United States)

    Wiles, David K.; Rockoff, Edward

    1977-01-01

    Explores the legal implications of in-school suspension practices through consideration of individual versus institutional rights within a special punitive-rehabilitative setting. Argues that the prison hospital model is applicable to in-school suspension programs and discusses a number of legal questions raised by the prison hospital model.…

  5. 12 CFR 513.4 - Suspension and debarment.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Suspension and debarment. 513.4 Section 513.4 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY PRACTICE BEFORE THE OFFICE § 513.4 Suspension and debarment. (a) The Office may censure any person practicing before it or may deny...

  6. Magnetic suspension of a rotating system. Application to inertial flywheels

    International Nuclear Information System (INIS)

    Lemarquand, Guy

    1984-01-01

    The various possible magnetic suspension configurations compatible with rotating mechanical systems are defined from studies of the characteristics of different types of magnetic bearings. The results obtained are used in the design and realization of a magnetic suspension for an inertial flywheel. (author) [fr

  7. 45 CFR 99.4 - Suspension of rules.

    Science.gov (United States)

    2010-10-01

    ... 45 Public Welfare 1 2010-10-01 2010-10-01 false Suspension of rules. 99.4 Section 99.4 Public Welfare DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL ADMINISTRATION PROCEDURE FOR HEARINGS FOR THE CHILD CARE AND DEVELOPMENT FUND General § 99.4 Suspension of rules. With notice to all parties, the...

  8. 2 CFR 180.740 - Are suspension proceedings formal?

    Science.gov (United States)

    2010-01-01

    ... 2 Grants and Agreements 1 2010-01-01 2010-01-01 false Are suspension proceedings formal? 180.740 Section 180.740 Grants and Agreements OFFICE OF MANAGEMENT AND BUDGET GOVERNMENTWIDE GUIDANCE FOR GRANTS... suspension decision. (b) You as a respondent or your representative must submit any documentary evidence you...

  9. 78 FR 15402 - Xytos, Inc.; Order of Suspension of Trading

    Science.gov (United States)

    2013-03-11

    ... SECURITIES AND EXCHANGE COMMISSION [ File No. 500-1] Xytos, Inc.; Order of Suspension of Trading... financial conditions and business operations, and because of potentially manipulative conduct in the trading... investors require a suspension of trading in the securities of the above-listed company. Therefore, it is...

  10. 75 FR 68636 - 8000, Inc.; Order of Suspension of Trading

    Science.gov (United States)

    2010-11-08

    ... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] 8000, Inc.; Order of Suspension of Trading... and the protection of investors require a suspension of trading in the securities of 8000, Inc. Therefore, it is ordered, pursuant to Section 12(k) of the Securities Exchange Act of 1934, that trading in...

  11. 77 FR 16113 - Asiamart, Inc., Order of Suspension of Trading

    Science.gov (United States)

    2012-03-19

    ... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] Asiamart, Inc., Order of Suspension of Trading... and the protection of investors require a suspension of trading in the securities of the above-listed... trading in the securities of the above-listed company is suspended for the period from 9:30 a.m. EDT on...

  12. 78 FR 44185 - RVPlus, Inc.; Order of Suspension of Trading

    Science.gov (United States)

    2013-07-23

    ... SECURITIES AND EXCHANGE COMMISSION [File No. 500-1] RVPlus, Inc.; Order of Suspension of Trading... and the protection of investors require a suspension of trading in the securities of the above-listed... trading in the securities of the above-listed company is suspended for the period from 9:30 a.m. EDT, on...

  13. 15 CFR 2011.110 - Suspension of certificate system.

    Science.gov (United States)

    2010-01-01

    ..., SYRUPS AND MOLASSES Certificate of Quota Eligibility § 2011.110 Suspension of certificate system. (a... of such suspension and the effective date thereof shall be published in the Federal Register. (b... such reinstatement and the effective date thereof shall be published in the Federal Register. (c...

  14. 19 CFR 210.23 - Suspension of investigation.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 3 2010-04-01 2010-04-01 false Suspension of investigation. 210.23 Section 210.23 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION INVESTIGATIONS OF UNFAIR PRACTICES IN IMPORT TRADE ADJUDICATION AND ENFORCEMENT Motions § 210.23 Suspension of investigation. Any party may move to...

  15. 3 CFR - Suspension of Limitations Under the Jerusalem Embassy Act

    Science.gov (United States)

    2010-01-01

    ... 3 The President 1 2010-01-01 2010-01-01 false Suspension of Limitations Under the Jerusalem... June 5, 2009 Suspension of Limitations Under the Jerusalem Embassy Act Memorandum for the Secretary of... States, including section 7(a) of the Jerusalem Embassy Act of 1995 (Public Law 104-45) (the “Act”), I...

  16. Non-homogeneous flow profiles in sheared bacterial suspensions

    Science.gov (United States)

    Samanta, Devranjan; Cheng, Xiang

    Bacterial suspensions under shear exhibit interesting rheological behaviors including the remarkable ``superfluidic'' state with vanishing viscosity at low shear rates. Theoretical studies have shown that such ``superfluidic'' state is linked with non-homogeneous shear flows, which are induced by coupling between nematic order of active fluids and hydrodynamics of shear flows. However, although bulk rheology of bacterial suspensions has been experimentally studied, shear profiles within bacterial suspensions have not been explored so far. Here, we experimentally investigate the flow behaviors of E. coli suspensions under planar oscillatory shear. Using confocal microscopy and PIV, we measure velocity profiles across gap between two shear plates. We find that with increasing shear rates, high-concentration bacterial suspensions exhibit an array of non-homogeneous flow behaviors like yield-stress flows and shear banding. We show that these non-homogeneous flows are due to collective motion of bacterial suspensions. The phase diagram of sheared bacterial suspensions is systematically mapped as functions of shear rates an bacterial concentrations. Our experiments provide new insights into rheology of bacterial suspensions and shed light on shear induced dynamics of active fluids. Chemical Engineering and Material Science department.

  17. Both Suspension and Alternatives Work, Depending on One's Aim

    Science.gov (United States)

    Bear, George G.

    2012-01-01

    In this commentary on the special series, I argue that whereas a zero-tolerance approach to school discipline is "something stupid" (Kauffman & Brigham, 2000) the use of suspension might not be. Despite its limitations, suspension and other forms of punishment serve as effective deterrents of behavior problems for most children, especially when…

  18. Network synthesis and parameter optimization for vehicle suspension with inerter

    Directory of Open Access Journals (Sweden)

    Long Chen

    2016-12-01

    Full Text Available In order to design a comfortable-oriented vehicle suspension structure, the network synthesis method was utilized to transfer the problem into solving a timing robust control problem and determine the structure of “inerter–spring–damper” suspension. Bilinear Matrix Inequality was utilized to obtain the timing transfer function. Then, the transfer function of suspension system can be physically implemented by passive elements such as spring, damper, and inerter. By analyzing the sensitivity and quantum genetic algorithm, the optimized parameters of inerter–spring–damper suspension were determined. A quarter-car model was established. The performance of the inerter–spring–damper suspension was verified under random input. The simulation results manifested that the dynamic performance of the proposed suspension was enhanced in contrast with traditional suspension. The root mean square of vehicle body acceleration decreases by 18.9%. The inerter–spring–damper suspension can inhibit the vertical vibration within the frequency of 1–3 Hz effectively and enhance the performance of ride comfort significantly.

  19. Tuning a Le Mans Car Suspension in ADAMS

    CSIR Research Space (South Africa)

    Berman, R

    2012-09-01

    Full Text Available An ADAMS model of South Africa’s first ever Le Mans car was developed and used to tune the suspension parameters. Validation of the model is to be done by comparing simulation results to those obtained in track testing. The suspension parameters...

  20. 26 CFR 301.6503(g)-1 - Suspension pending correction.

    Science.gov (United States)

    2010-04-01

    ... 26 Internal Revenue 18 2010-04-01 2010-04-01 false Suspension pending correction. 301.6503(g)-1 Section 301.6503(g)-1 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED... Collection § 301.6503(g)-1 Suspension pending correction. The running of the periods of limitations provided...

  1. 21 CFR 1314.155 - Suspension pending final order.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Suspension pending final order. 1314.155 Section 1314.155 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE RETAIL SALE OF SCHEDULED LISTED CHEMICAL PRODUCTS Order to Show Cause § 1314.155 Suspension pending final order. (a) The...

  2. 21 CFR 520.1182 - Iron dextran suspension.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Iron dextran suspension. 520.1182 Section 520.1182... DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1182 Iron dextran suspension... hydroxide in complex with a low molecular weight dextran. (b) Sponsor. See No. 051311 in § 510.600(c) of...

  3. Degradability of aged aquatic suspensions of C60 nanoparticles

    DEFF Research Database (Denmark)

    Hartmann, Nanna Isabella Bloch; Buendia, Inmaculada M.; Bak, Jimmy

    2011-01-01

    In this study, aged aqueous suspensions of C(60) (nC(60)) were investigated in the respirometric OECD test for ready biodegradability. Two suspensions of nC(60) were prepared by stirring and aged under indirect exposure to sunlight for 36 months. ATR-FTIR analyses confirmed the presence of C(60)-...

  4. Radiation resistivity of frozen insulin solutions and suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Soboleva, N N; Ivanova, A I; Talrose, V L; Trofimov, V I; Fedotov, V P [AN SSSR, Moscow. Inst. Fizicheskoj Khimii; Research Institute for Biological Testing of Chemicals, Moscow (USSR); Institute of Experimental Endocrinology and Hormon Chemistry, Moscow (USSR))

    1981-10-01

    The effect of great increase in radiation resistance of insulin solutions and suspensions after irradiation at low temperatures in the frozen state was observed by absorption spectrophotometry, paper chromatography and biological analysis. The data obtained suggest irradiation of frozen insulin solutions and suspensions as a method for its sterilization.

  5. 38 CFR 21.3043 - Suspension of program; child.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Suspension of program; child. 21.3043 Section 21.3043 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... 38 U.S.C. Chapter 35 Eligibility and Entitlement § 21.3043 Suspension of program; child. For an...

  6. Research on Dynamic Optimization for Road-friendly Vehicle Suspension

    Directory of Open Access Journals (Sweden)

    Lu Yongjie

    2014-10-01

    Full Text Available The heavy vehicle brings large dynamic loads to the road surface, which would reduce vehicle ride comfort and shorten road service life. The structure characteristic of heavy vehicle suspension has a significant impact on vehicle performance. Based on the D'Alembert principle, the dynamics models of independent and integral balanced suspension are proposed considering mass and inertia of balancing rod. The sprung mass acceleration and the tire dynamic force for two kinds of balanced suspension and the traditional quarter vehicle model are compared in frequency-domain and time-domain respectively. It is concluded that a quarter vehicle model simplified for balanced suspension could be used to evaluate the ride comfort of vehicle well, but it has some limitations in assessing the vehicle road-friendliness. Then, the sprung mass acceleration and the road damage coefficients are also analyzed under different vehicle design and running parameters at detail. Some conclusions are obtained: low suspension stiffness, high suspension damping and low tire stiffness are all favorable to improve vehicle performance; there is a saturation range of suspension damping enhancing vehicle performance; improving the road surface roughness and avoiding the no-load running are two effective methods to accomplish the better ride comfort and road-friendliness. The suspension stiffness and damping parameters are chosen for optimal parameters matching of road friendliness based on the approximation optimization method.

  7. Effects of the finite particle size in turbulent wall-bounded flows of dense suspensions

    Science.gov (United States)

    Costa, Pedro; Picano, Francesco; Brandt, Luca; Breugem, Wim-Paul

    2018-05-01

    We use interface-resolved simulations to study finite-size effects in turbulent channel flow of neutrally-buoyant spheres. Two cases with particle sizes differing by a factor of 2, at the same solid volume fraction of 20% and bulk Reynolds number are considered. These are complemented with two reference single-phase flows: the unladen case, and the flow of a Newtonian fluid with the effective suspension viscosity of the same mixture in the laminar regime. As recently highlighted in Costa et al. (PRL 117, 134501), a particle-wall layer is responsible for deviations of the statistics from what is observed in the continuum limit where the suspension is modeled as a Newtonian fluid with an effective viscosity. Here we investigate the fluid and particle dynamics in this layer and in the bulk. In the particle-wall layer, the near wall inhomogeneity has an influence on the suspension micro-structure over a distance proportional to the particle size. In this layer, particles have a significant (apparent) slip velocity that is reflected in the distribution of wall shear stresses. This is characterized by extreme events (both much higher and much lower than the mean). Based on these observations we provide a scaling for the particle-to-fluid apparent slip velocity as a function of the flow parameters. We also extend the flow scaling laws in to second-order Eulerian statistics in the homogeneous suspension region away from the wall. Finite-size effects in the bulk of the channel become important for larger particles, while negligible for lower-order statistics and smaller particles. Finally, we study the particle dynamics along the wall-normal direction. Our results suggest that 1-point dispersion is dominated by particle-turbulence (and not particle-particle) interactions, while differences in 2-point dispersion and collisional dynamics are consistent with a picture of shear-driven interactions.

  8. An Ultra-low Frequency Modal Testing Suspension System for High Precision Air Pressure Control

    Directory of Open Access Journals (Sweden)

    Qiaoling YUAN

    2014-05-01

    Full Text Available As a resolution for air pressure control challenges in ultra-low frequency modal testing suspension systems, an incremental PID control algorithm with dead band is applied to achieve high-precision pressure control. We also develop a set of independent hardware and software systems for high-precision pressure control solutions. Taking control system versatility, scalability, reliability, and other aspects into considerations, a two-level communication employing Ethernet and CAN bus, is adopted to complete such tasks as data exchange between the IPC, the main board and the control board ,and the pressure control. Furthermore, we build a single set of ultra-low frequency modal testing suspension system and complete pressure control experiments, which achieve the desired results and thus confirm that the high-precision pressure control subsystem is reasonable and reliable.

  9. Growth kinetics of tin oxide nanocrystals in colloidal suspensions under hydrothermal conditions

    International Nuclear Information System (INIS)

    Lee, Eduardo J.H.; Ribeiro, Caue; Longo, Elson; Leite, Edson R.

    2006-01-01

    Colloidal suspensions of tin oxide nanocrystals were synthesized at room temperature by the hydrolysis reaction of tin chloride (II), in an ethanolic solution. The coarsening kinetics of such nanocrystals was studied by submitting the as-prepared suspensions to hydrothermal treatments at temperatures of 100, 150 and 200 deg. C for periods between 60 and 12,000 min. Transmission electron microscopy (TEM) was used to characterize the samples (i.e. distribution of nanocrystal size, average particle radius and morphology). The results show that the usual Ostwald ripening coarsening mechanism does not fit well the experimental data, which is an indicative that this process is not significant for SnO 2 nanocrystals, in the studied experimental conditions. The morphology evolution of the nanocrystals upon hydrothermal treatment indicates that growth by oriented attachment (OA) should be significant. A kinetic model that describes OA growth is successfully applied to fit the data

  10. Effective delivery of sonication energy to fast settling and agglomerating nanomaterial suspensions for cellular studies: Implications for stability, particle kinetics, dosimetry and toxicity.

    Science.gov (United States)

    Cohen, Joel M; Beltran-Huarac, Juan; Pyrgiotakis, Georgios; Demokritou, Philip

    2018-04-01

    Typical in vitro assays used for high throughput toxicological screening and measuring nano-bio interactions are conducted by pipetting suspensions of engineered nanomaterials (ENMs) dispersed in nutrient-rich culture media directly onto cells. In order to achieve fairly monodisperse and stable suspensions of small agglomerates, ultrasonic energy is usually applied to break apart large agglomerates that can form upon suspension in liquid. Lack of standardized protocols and methods for delivering sonication energy can introduce variability in the ENM suspension properties ( e.g . agglomerate size, polydispersity, suspension stability over time), and holds significant implications for in vitro dosimetry, toxicity, and other nano-bio interactions. Careful assessment of particle transformations during dispersion preparation and sonication is therefore critical for accurate interpretation of in vitro toxicity studies. In this short communication, the difficulties of preparing stable suspensions of rapidly settling ENMs are presented. Furthermore, methods to optimize the delivery of the critical sonication energy required to break large agglomerates and prepare stable, fairly monodispersed suspensions of fast settling ENMs are presented. A methodology for the efficient delivery of sonication energy in a discrete manner is presented and validated using various rapidly agglomerating and settling ENMs. The implications of continuous vs. discrete sonication on average hydrodynamic diameter, and polydispersity was also assessed for both fast and slow settling ENMs. For the rapidly agglomerating and settling ENMs (Ag15%/SiO 2 , Ag and CeO 2 ), the proposed discrete sonication achieved a significant reduction in the agglomerate diameter and polydispersity. In contrast, the relatively slow agglomerating and settling Fe 2 O 3 suspension did not exhibit statistically significant differences in average hydrodynamic diameter or polydispersity between the continuous and discrete

  11. Vaginal vault suspension during hysterectomy for benign indications

    DEFF Research Database (Denmark)

    Bonde, Lisbeth; Noer, Mette Calundann; Møller, Lars Alling

    2017-01-01

    Introduction and hypothesis: Several suspension methods are used to try to prevent pelvic organ prolapse (POP) after hysterectomy. We aimed to evaluate agreement on terminology and surgical procedure of these methods. Methods: We randomly chose 532 medical records of women with a history......: Regarding medical records, agreement on terminology was good among patients undergoing pooled suspension in cases of hysterectomy via the abdominal and vaginal route (agreement 78.7, 92.3%). Regarding videos, agreement on surgical procedure was good among pooled suspension patients in cases of hysterectomy...... via the abdominal, laparoscopic, and vaginal routes (agreement 88.9, 97.8, 100%). Agreement on individual suspension methods differed regarding both medical records (agreement 0–90.1%) and videos (agreement 0–100%). Conclusions: Agreement on terminology and surgical procedure regarding suspension...

  12. Preparation of conjugated polymer suspensions by using ultrasonic atomizer

    Energy Technology Data Exchange (ETDEWEB)

    Tada, Kazuya, E-mail: tada@eng.u-hyogo.ac.jp; Onoda, Mitsuyoshi

    2010-11-30

    The electrophoretic deposition is a method useful to prepare conjugated polymer films for electronic devices. This method provides high material recovery rate on the substrate from the suspension, in contrast to the conventional spin-coating in which most of the material placed on the substrate is blown away. Although manual reprecipitation technique successfully yields suspensions of various conjugated polymers including polyfluorene derivatives, it is favorable to control the preparation process of suspensions. In this context, this paper reports preliminary results on the preparation of suspension of conjugated polymer by using an ultrasonic atomizer. While the resultant films do not show particular difference due to the preparation methods of the suspension, the electric current profiles during the electrophoretic deposition suggests that the ultrasonic atomization of polymer solution prior to be mixed with poor solvent results in smaller and less uniform colloidal particles than the conventional manual pouring method.

  13. Control of Chaos: New Perspectives in Experimental and Theoretical Science. International Journal of Bifurcation and Chaos in Applied Sciences and Engineering. Theme Issue. Part 1. Volume 8, Number 8, August 1998

    National Research Council Canada - National Science Library

    Arecchi, F

    1998-01-01

    .... In every field of the applied sciences (astronomy, atmospheric sciences, biology, chemistry, economics, geophysics, life and medical sciences, physics, social sciences, zoology, etc.) and engTheenng...

  14. The analysis of silica suspensions atomization

    Energy Technology Data Exchange (ETDEWEB)

    Ochowiak, M., E-mail: Marek.Ochowiak@put.poznan.pl [Poznan University of Technology, Faculty of Chemical Technology, Department of Chemical Engineering and Equipment, Poznan (Poland); Broniarz-Press, L.; Woziwodzki, S. [Poznan University of Technology, Faculty of Chemical Technology, Department of Chemical Engineering and Equipment, Poznan (Poland)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer The correlation equation for discharge coefficient has been proposed. Black-Right-Pointing-Pointer The spray angle increases with increase in GLR until a maximum value is attained at GLR value of 0.07. Black-Right-Pointing-Pointer The equation for SMD has been proposed. Black-Right-Pointing-Pointer The C{sub D} and SMD are decreasing rapidly as GLR is increased to around 0.07 and thereafter decreasing at a slower rate. - Abstract: The paper contains the results of experimental investigation of air-water and air-silica suspension atomization process in effervescent nozzles with internal mixing obtained by the use of the digital microphotography method. In experiments the different aqueous solutions of silica Aerosil 300 of different concentration have been used. The suspensions containing up to 0.04 (kg solid particles/kg solution) have Newtonian rheological properties. The observations were carried out at liquid flow rates changed from 0.0014 to 0.011 (kg/s) and gas flow rates from 0.00015 to 0.0065 (kg/s). It corresponded to gas to liquid mass ratios (GLR) values from 0.014 to 0.46. The analysis of photos shows that the droplets which have been formed during the liquid atomization have very different sizes. The differences between characteristics of effervescent atomization for water and suspensions used have not been observed. The present study confirmed the previous reports which suggested that the small particles added to solution do not change spray characteristics. The experimental results show that C{sub D} and SMD are non-linear functions of GLR. Their values are decreasing rapidly as GLR is increased from zero to around 0.07 and thereafter decreasing at a slower rate with further increase in GLR. In the same point (GLR = 0.07) the value of {alpha} is maximal. The first regime is characteristic for bubbly flow. The second is typical of annular flow regime. Boundary between bubbly and annular flow regime is observed

  15. Adaptive magnetorheological seat suspension for shock mitigation

    Science.gov (United States)

    Singh, Harinder Jit

    This research focuses on theoretical and experimental analysis of an adaptive seat suspension employing magnetorheological energy absorber with the objective of minimizing injury potential to seated occupant of different weights subjected to broader crash intensities. The research was segmented into three tasks: (1) development of magnetorheological energy absorber, (2) biodynamic modeling of a seated occupant, and (3) control schemes for shock mitigation. A linear stroking semi-active magnetorheological energy absorber (MREA) was designed, fabricated and tested for intense impact conditions with piston velocities up to 8 m/s. MREA design was optimized on the basis of Bingham-plastic model (BPM model) in order to maximize the energy absorption capabilities at high impact velocities. Computational fluid dynamics and magnetic FE analysis were conducted to validate MREA performance. Subsequently, low-speed cyclic testing (0-2 Hz subjected to 0-5.5 A) and high-speed drop testing (0-4.5 m/s at 0 A) were conducted for quantitative comparison with the numerical simulations. Later, a nonlinear four degrees-of-freedom biodynamic model representing a seated 50th percentile male occupant was developed on the basis of experiments conducted on Hybrid II 50th percentile male anthropomorphic test device. The response of proposed biodynamic model was compared quantitatively against two different biodynamic models from the literature that are heavily implemented for obtaining biodynamic response under impact conditions. The proposed biodynamic model accurately predicts peak magnitude, overall shape and the duration of the biodynamic transient response, with minimal phase shift. The biodynamic model was further validated against 16 impact tests conducted on horizontal accelerator facility at NAVAIR for two different shock intensities. Compliance effects of human body were also investigated on the performance of adaptive seat suspension by comparing the proposed biodynamic model

  16. Applied mathematics

    International Nuclear Information System (INIS)

    Nedelec, J.C.

    1988-01-01

    The 1988 progress report of the Applied Mathematics center (Polytechnic School, France), is presented. The research fields of the Center are the scientific calculus, the probabilities and statistics and the video image synthesis. The research topics developed are: the analysis of numerical methods, the mathematical analysis of the physics and mechanics fundamental models, the numerical solution of complex models related to the industrial problems, the stochastic calculus and the brownian movement, the stochastic partial differential equations, the identification of the adaptive filtering parameters, the discrete element systems, statistics, the stochastic control and the development, the image synthesis techniques for education and research programs. The published papers, the congress communications and the thesis are listed [fr

  17. Development of the Nissan hydraulic active suspension. Nissan yuatsu active suspension no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kawarasaki, y.; Fukunaga, Y.; Hasegawa, S.; Okuyama, Y.; Omura, I.; Takahashi, K.; Abe, S.; Tsuruta, E. (Nissan Motor Co. Ltd., Tokyo (Japan))

    1989-12-25

    A hydraulic active suspension system, Nissan original product, was developed and mass produced for the first time in the world. The system incorporates a sufficient power source, a high accuracy sensor and a high response device for continuous and intended vehicle control and at the same time delivers high levels of ride comfort and driving performance. The suspension system has four innovative features: skyhook damping, active roll and pitching control, a frequency-dependent damping mechanism, and active steering characteristics control. Under all road and operating conditions, the system actively suppresses vehicle attitude changes and unnecessary movement, and also gently absorbs inputs from the road. This epoch-making system provides a dramatic improvement in vehicle performance, and has been adopted in the Infiniti Q45 luxury sedan. 2 refs., 20 figs., 4 tabs.

  18. Reachable volume RRT

    KAUST Repository

    McMahon, Troy

    2015-05-01

    © 2015 IEEE. Reachable volumes are a new technique that allows one to efficiently restrict sampling to feasible/reachable regions of the planning space even for high degree of freedom and highly constrained problems. However, they have so far only been applied to graph-based sampling-based planners. In this paper we develop the methodology to apply reachable volumes to tree-based planners such as Rapidly-Exploring Random Trees (RRTs). In particular, we propose a reachable volume RRT called RVRRT that can solve high degree of freedom problems and problems with constraints. To do so, we develop a reachable volume stepping function, a reachable volume expand function, and a distance metric based on these operations. We also present a reachable volume local planner to ensure that local paths satisfy constraints for methods such as PRMs. We show experimentally that RVRRTs can solve constrained problems with as many as 64 degrees of freedom and unconstrained problems with as many as 134 degrees of freedom. RVRRTs can solve problems more efficiently than existing methods, requiring fewer nodes and collision detection calls. We also show that it is capable of solving difficult problems that existing methods cannot.

  19. Reachable volume RRT

    KAUST Repository

    McMahon, Troy; Thomas, Shawna; Amato, Nancy M.

    2015-01-01

    © 2015 IEEE. Reachable volumes are a new technique that allows one to efficiently restrict sampling to feasible/reachable regions of the planning space even for high degree of freedom and highly constrained problems. However, they have so far only been applied to graph-based sampling-based planners. In this paper we develop the methodology to apply reachable volumes to tree-based planners such as Rapidly-Exploring Random Trees (RRTs). In particular, we propose a reachable volume RRT called RVRRT that can solve high degree of freedom problems and problems with constraints. To do so, we develop a reachable volume stepping function, a reachable volume expand function, and a distance metric based on these operations. We also present a reachable volume local planner to ensure that local paths satisfy constraints for methods such as PRMs. We show experimentally that RVRRTs can solve constrained problems with as many as 64 degrees of freedom and unconstrained problems with as many as 134 degrees of freedom. RVRRTs can solve problems more efficiently than existing methods, requiring fewer nodes and collision detection calls. We also show that it is capable of solving difficult problems that existing methods cannot.

  20. Defect Proliferation in Active Nematic Suspensions

    Science.gov (United States)

    Mishra, Prashant; Bowick, Mark J.; Giomi, Luca; Marchetti, M. Cristina

    2014-03-01

    The rich structure of equilibrium nematic suspensions, with their characteristic disclination defects, is modified when active forces come into play. The uniform nematic state is known to be unstable to splay (extensile) or bend (contractile) deformations above a critical activity. At even higher activity the flow becomes oscillatory and eventually turbulent. Using hydrodynamics, we classify the active flow regimes as functions of activity and order parameter friction for both contractile and extensile systems. The turbulent regime is marked by a non-zero steady state density of mobile defect pairs. The defect density itself scales with an ``active Ericksen number,'' defined as the ratio of the rate at which activity is injected into the system to the relaxation rate of orientational deformations. The work at Syracuse University was supported by the NSF on grant DMR-1004789 and by the Syracuse Soft Matter Program.

  1. Flight suspension for the relativity gyro

    International Nuclear Information System (INIS)

    Patten, R.A. van

    1983-01-01

    A suspension system for levitation and precision positioning of the niobium coated spherical quartz gyro rotor during orbital flight has been simulated. The system employs multiple controllers and estimators with microprocessor (Z80) controlled range switching. The resulting system handles external accelerations up to 1 g in the highest range yet in the lowest range, below 10 -6 g the sensor noise power spectral density produces only 10 -10 g rms in the rotor. The system is capable of automatic emergency switch up within 100 μsec. Switch down is automatic to expected flight levels of ± 5 x 10 -8 g. Positioning accuracy in all ranges including emergency switch up is ± 5 μin. static, and ± 50 μin. dynamic. The average acceleration during the mission should be 10 -10 g to attain the science data accuracy goal. (Auth.)

  2. Mirror suspension system for the TAMA SAS

    CERN Document Server

    Takamori, A; Bertolini, A; Cella, G; DeSalvo, R; Fukushima, M; Iida, Y; Jacquier, F; Kawamura, S; Marka, S; Nishi, Y; Numata, K; Sannibale, V; Somiya, K; Takahashi, R; Tariq, H; Tsubono, K; Ugas, J; Viboud, N; Yamamoto, H; Yoda, T; Wang Chen Yang

    2002-01-01

    Several R and D programmes are ongoing to develop the next generation of interferometric gravitational wave detectors providing the superior sensitivity desired for refined astronomical observations. In order to obtain a wide observation band at low frequencies, the optics need to be isolated from the seismic noise. The TAMA SAS (seismic attenuation system) has been developed within an international collaboration between TAMA, LIGO, and some European institutes, with the main objective of achieving sufficient low-frequency seismic attenuation (-180 dB at 10 HZ). The system suppresses seismic noise well below the other noise levels starting at very low frequencies above 10 Hz. It also includes an active inertial damping system to decrease the residual motion of the optics enough to allow a stable operation of the interferometer. The TAMA SAS also comprises a sophisticated mirror suspension subsystem (SUS). The SUS provides support for the optics and vibration isolation complementing the SAS performance. The SU...

  3. Aeroelastic Stability of Suspension Bridges using CFD

    DEFF Research Database (Denmark)

    Stærdahl, Jesper Winther; Sørensen, Niels; Nielsen, Søren R.K.

    2007-01-01

    using CFD models and the aeroelastic stability boundary has been successfully determined when comparing two-dimensional flow situations using wind tunnel test data and CFD methods for the flow solution and two-degrees-of-freedom structural models in translation perpendicular to the flow direction......In recent years large span suspension bridges with very thin and slender profiles have been built without proportional increasing torsional and bending stiffness. As a consequence large deformations at the mid-span can occur with risk of aeroelastic instability and structural failure. Analysis...... of aeroelastic stability also named flutter stability is mostly based on semi-empirical engineering models, where model specific parameters, the so-called flutter derivatives, need calibration from wind tunnel tests or numerical methods. Several papers have been written about calibration of flutter derivatives...

  4. Assessment of drug salt release from solutions, suspensions and in situ suspensions using a rotating dialysis cell

    DEFF Research Database (Denmark)

    Parshad, Henrik; Frydenvang, Karla; Liljefors, Tommy

    2003-01-01

    buffer is used as release media. Generally, the initial release of the drug salt from in situ suspensions occurred faster as compared to conventional suspensions, probably due to incomplete precipitation of the drug salt, and hence formation of supersaturated solutions where the rate of release......A rotating dialysis cell consisting of a small (10 ml) and a large compartment (1000 ml) was used to study the release of drug salt (bupivacaine 9-anthracene carboxylate) from (i). solutions, (ii). suspensions and (iii). in situ formed suspensions. Initial release experiments from suspensions...... indicated that the release of drug salt in deionized water was predominantly limited by the diffusion across the membrane whereas it is essentially dissolution rate controlled in 0.05 M phosphate buffer (pH 7.40). Thus, the in vitro model appears to have a potential in formulation screening when phosphate...

  5. Degree of mucosal coating on double contrast barium enema : comparison of distilled water and normal saline as a suspension

    International Nuclear Information System (INIS)

    Seo, Tae Seok; Lee, Dong Ho; Ko, Young Tae; Lim, Joo Won; Han, Tae Il; Kim, Hyoung Jung

    1997-01-01

    To evaluate the degree of mucosal coating on double contrast barium enema (DCBE), using barium suspension made with distilled water or normal saline Between June 1 and July 30, 1996, fifty-four patients prospectively underwent DCBE using 83% w/v(weight-to-volume) of barium suspension (room temperature, 24 deg C), which was made with 1,200mL of distilled water (Group 1;29cases) and normal saline (Group 2;25cases) per 1Kg of Solotop (Taejoon Pharmacy, Seoul, Korea). Bowel preparation and examination methods were the same in both groups, and four projections(erect view, supine view, both decubitus views) were taken. The mucosal coating was graded as excellent, good, ordinary, or poor by three radiologists working independently, and scored from 3 to 0. Significance was analyzed by t-test. Mean grading scores were 2.33±0.70 in group 1 and 1.56±0.99 in group 2 (P<0.003). When barium suspension made with distilled water was used, the degree of mucosal coating on DCBE was better than when the suspension was made with normal saline

  6. Hindrance Velocity Model for Phase Segregation in Suspensions of Poly-dispersed Randomly Oriented Spheroids

    Science.gov (United States)

    Faroughi, S. A.; Huber, C.

    2015-12-01

    Crystal settling and bubbles migration in magmas have significant effects on the physical and chemical evolution of magmas. The rate of phase segregation is controlled by the force balance that governs the migration of particles suspended in the melt. The relative velocity of a single particle or bubble in a quiescent infinite fluid (melt) is well characterized; however, the interplay between particles or bubbles in suspensions and emulsions and its effect on their settling/rising velocity remains poorly quantified. We propose a theoretical model for the hindered velocity of non-Brownian emulsions of nondeformable droplets, and suspensions of spherical solid particles in the creeping flow regime. The model is based on three sets of hydrodynamic corrections: two on the drag coefficient experienced by each particle to account for both return flow and Smoluchowski effects and a correction on the mixture rheology to account for nonlocal interactions between particles. The model is then extended for mono-disperse non-spherical solid particles that are randomly oriented. The non-spherical particles are idealized as spheroids and characterized by their aspect ratio. The poly-disperse nature of natural suspensions is then taken into consideration by introducing an effective volume fraction of particles for each class of mono-disperse particles sizes. Our model is tested against new and published experimental data over a wide range of particle volume fraction and viscosity ratios between the constituents of dispersions. We find an excellent agreement between our model and experiments. We also show two significant applications for our model: (1) We demonstrate that hindered settling can increase mineral residence time by up to an order of magnitude in convecting magma chambers. (2) We provide a model to correct for particle interactions in the conventional hydrometer test to estimate the particle size distribution in soils. Our model offers a greatly improved agreement with

  7. Numerical and experimental analysis of the sedimentation of spherical colloidal suspensions under centrifugal force

    Science.gov (United States)

    Antonopoulou, Evangelia; Rohmann-Shaw, Connor F.; Sykes, Thomas C.; Cayre, Olivier J.; Hunter, Timothy N.; Jimack, Peter K.

    2018-03-01

    Understanding the sedimentation behaviour of colloidal suspensions is crucial in determining their stability. Since sedimentation rates are often very slow, centrifugation is used to expedite sedimentation experiments. The effect of centrifugal acceleration on sedimentation behaviour is not fully understood. Furthermore, in sedimentation models, interparticle interactions are usually omitted by using the hard-sphere assumption. This work proposes a one-dimensional model for sedimentation using an effective maximum volume fraction, with an extension for sedimentation under centrifugal force. A numerical implementation of the model using an adaptive finite difference solver is described. Experiments with silica suspensions are carried out using an analytical centrifuge. The model is shown to be a good fit with experimental data for 480 nm spherical silica, with the effects of centrifugation at 705 rpm studied. A conversion of data to Earth gravity conditions is proposed, which is shown to recover Earth gravity sedimentation rates well. This work suggests that the effective maximum volume fraction accurately captures interparticle interactions and provides insights into the effect of centrifugation on sedimentation.

  8. Solvent-mediated pathways to gelation and phase separation in suspensions of grafted nanoparticles

    KAUST Repository

    Anyfantakis, Manos

    2009-01-01

    We explore the role of the solvent medium on the interplay between gelation and phase separation in suspensions of organosilicate planar hybrids grafted with hydrocarbon chains. We establish their phase diagram by means of dynamic light scattering, rheology and visual observations, and different routes to gelation, depending on the solvent used. In agreement with earlier works, the solvent quality for the grafted chains at a given temperature controls the balance between attractions and repulsions, and hence the phase diagram of the nanoparticles and their tendency to gel. Here we show how to tune the suspension state and hence its rheology. For decane, a good solvent for the hydrocarbon chains, gelation occurs at rather low volume fractions in the presence of phase separation. This is due to the interdigitation of solvent molecules with the grafted chains, resulting in their crystalline packing that promotes the attraction between particles. For toluene, a solvent of reduced quality for the hydrocarbon chains, no interdigitation takes place, and hence gelation is triggered by clustering at higher volume fractions before phase separation. Our results support the generic picture of complex kinetic arrest/phase separation interplay in soft matter, where phase separation can proceed, be interrupted or be completely inhibited. A number of interesting possibilities for tailoring the rheology of grafted colloidal systems emerge. © 2009 The Royal Society of Chemistry.

  9. Optimal design of MR shock absorber and application to vehicle suspension

    International Nuclear Information System (INIS)

    Nguyen, Quoc-Hung; Choi, Seung-Bok

    2009-01-01

    This paper presents an optimal design of a magnetorheological (MR) shock absorber based on finite element analysis. The MR shock absorber is constrained in a specific volume and the optimization problem identifies geometric dimensions of the shock absorber that minimize a multi-objective function. The objective function is proposed by considering the damping force, dynamic range and the inductive time constant of the shock absorber. After describing the configuration of the MR shock absorber, a quasi-static modeling of the shock absorber is performed based on the Bingham model of an MR fluid. The initial geometric dimensions of the shock absorber are then determined based on the assumption of constant magnetic flux density throughout the magnetic circuit. The objective function of the optimization problem is derived based on the solution of the initial shock absorber. An optimization procedure using a golden-section algorithm and a local quadratic fitting technique is constructed via a commercial finite element method parametric design language. Using the developed optimization tool, optimal solutions of the MR shock absorber, which is constrained in a specific cylindrical volume defined by its radius and height, are determined. Subsequently, a quarter-car suspension model with the optimized MR shock absorber is formulated and the vibration control performance of the suspension is evaluated under bump and sinusoidal road conditions

  10. Enhancement of stability of various nZVI suspensions used in groundwater remediation with environmentally friendly organic stabilizers

    Science.gov (United States)

    Schmid, Doris; Wagner, Stephan; Velimirović, Milica; Laumann, Susanne; Micić, Vesna; Hofmann, Thilo

    2014-05-01

    The use of nanoscale zero-valent iron (nZVI) particles for in situ remediation of polluted soil and groundwater has been shown as one of the most promising techniques [1]. The success of this technology depends on the mobility, reactivity, and longevity of nZVI particles. The mobility of nZVI particles depends on the properties of the single particles, stability of the particle suspension, and the aquifer material [1,2]. In order to enhance the mobility of nZVI, the mobility-decisive properties of the nZVI particles in suspension such as concentration, size distribution, surface charge, and sedimentation rate have to be investigated and optimized. Previous studies showed that pristine nZVI particles aggregate rapidly in water, reducing the particles radius of influence after injection [3]. In order to prevent aggregation and sedimentation of the nZVI particles, and consequently improve the stability of nZVI suspension and therefore the mobility of the nZVI particles, surface stabilizers can be used to provide electrostatic repulsion and steric or electrosteric stabilization [3,4]. The objective of this lab-scale study is to investigate the potential for enhancing the stability of different nZVI suspensions by means of environmentally friendly organic stabilizers, including carboxymethyl cellulose, pectin, alginate, xanthan, and guar gum. The different nZVI particles used included pristine and polyacrylic acid-coated nZVI particles provided in suspension (Nanofer 25 and Nanofer 25S, respectively, NANOIRON s.r.o., Czech Republic), air-stable nZVI particles (Nanofer Star, (NANOIRON s.r.o., Czech Republic), and milled iron flakes (UVR-FIA, Germany). In order to study the enhancement of nZVI stability (1 g L-1 total iron) different concentrations of organic stabilizers (1-20 wt.%) were applied in these nZVI suspensions. Each nZVI suspension was freshly prepared and treated for 10 minutes with Ultra-Turrax (15 000 rpm) and 10 minutes ultrasonic bath prior to

  11. Determination of acoustic fields in acidic suspensions of peanut shell during pretreatment with high-intensity ultrasound

    Directory of Open Access Journals (Sweden)

    Tiago Carregari Polachini

    Full Text Available Abstract The benefits of high-intensity ultrasound in diverse processes have stimulated many studies based on biomass pretreatment. In order to improve processes involving ultrasound, a calorimetric method has been widely used to measure the real power absorbed by the material as well as the cavitation effects. Peanut shells, a byproduct of peanut processing, were immersed in acidified aqueous solutions and submitted to an ultrasonic field. Acoustic power absorbed, acoustic intensity and power yield were obtained through specific heat determination and experimental data were modeled in different conditions. Specific heat values ranged from 3537.0 to 4190.6 J·kg-1·K-1, with lower values encountered for more concentrated biomass suspensions. The acoustic power transmitted and acoustic intensity varied linearly with the applied power and quadratically with solids concentration, reaching maximum values at higher applied nominal power and for less concentrated suspensions. A power yield of 82.7% was reached for dilute suspensions at 320 W, while 6.4% efficiency was observed for a concentrated suspension at low input energy (80 W.

  12. Ceramic Near-Net Shaped Processing Using Highly-Loaded Aqueous Suspensions

    Science.gov (United States)

    Rueschhoff, Lisa

    Ceramic materials offer great advantages over their metal counterparts, due to their lower density, higher hardness and wear resistance, and higher melting temperatures. However, the use of ceramics in applications where their properties would offer tremendous advantages are often limited due to the difficulty of forming them into complex and near-net shaped parts. Methods that have been developed to injection-mold or cast ceramics into more complicated shapes often use significant volume fractions of a carrier (often greater than 35 vol.% polymer), elevated temperature processing, or less-than-environmentally friendly chemicals where a complex chemical synthesis reaction must be timed perfectly for the approach to work. Furthermore, the continuing maturation of additive manufacturing methods requires a new approach for flowing/placing ceramic powders into useful designs. This thesis addresses the limitations of the current ceramic forming approaches by developing highly-stabilized and therefore high solids loading ceramic suspensions, with the requisite rheology for a variety of complex and near-net shaped forming techniques. Silicon nitride was chosen as a material of focus due to its high fracture toughness compared to other ceramic materials. Designing ceramic suspensions that are flowable at room temperature greatly simplifies processing as neither heating nor cooling are required during forming. Highly-loaded suspensions (>40 vol.%) are desired because all formed ceramic bodies have to be sintered to remove pores. Finally, using aqueous-based suspensions reduces any detrimental effect on the environment and tooling. The preparation of highly-loaded suspensions requires the development of a suitable dispersant through which particle-particle interactions are controlled. However, silicon nitride is difficult to stabilize in water due to complex surface and solution chemistry. In this study, aqueous silicon nitride suspensions up to 45 vol.% solids loading were

  13. Fast Evaporation of Spreading Droplets of Colloidal Suspensions

    Science.gov (United States)

    Maki, Kara; Kumar, Satish

    2011-11-01

    When a coffee droplet dries on a countertop, a dark ring of coffee solute is left behind, a phenomenon often referred to as ``the coffee-ring effect.'' A closely related yet less-well-explored phenomenon is the formation of a layer of particles, or skin, at the surface of the droplet. In this work, we explore the behavior of a mathematical model that can qualitatively describe both phenomena. We consider a thin axisymmetric droplet of a colloidal suspension on a horizontal substrate undergoing spreading and rapid evaporation. The lubrication approximation is applied to simplify the mass and momentum conservation equations, and the colloidal particles are allowed to influence droplet rheology through their effect on the viscosity. By describing the transport of the colloidal particles with the full convection-diffusion equation, we are able to capture depthwise gradients in particle concentration and thus describe skin formation, a feature neglected in prior models of droplet evaporation. Whereas capillarity creates a flow that drives particles to the contact line to produce a coffee-ring, Marangoni flows can compete with this and promote skin formation. Increases in viscosity due to particle concentration slow down droplet dynamics, and can lead to a significant reduction in the spreading rate.

  14. Preparation of Water Suspensions of Nanocalcite for Cultural Heritage Applications

    Directory of Open Access Journals (Sweden)

    Maria-Beatrice Coltelli

    2018-04-01

    Full Text Available The consolidation of degraded carbonate stone used in ancient monuments is an important topic for European cultural heritage conservation. The products most frequently used as consolidants are based on tetraalkoxy- or alkylalkoxy-silanes (in particular tetraethyl-orthosilicate, TEOS, resulting in the formation of relatively stable amorphous silica or alkylated (hydrophobic silica inside the stone pores. However, silica is not chemically compatible with carbonate stones; in this respect, nanocalcite may be a suitable alternative. The present work concerns the preparation of water suspensions of calcite nanoparticles (CCNPs by controlled carbonation of slaked lime using a pilot-scale reactor. A simplified design of experiment was adopted for product optimization. Calcite nanoparticles of narrow size distribution averaging about 30 nm were successfully obtained, the concentration of the interfacial agent and the size of CaO being the most critical parameters. Primary nanoparticle aggregation causing flocculation could be substantially prevented by the addition of polymeric dispersants. Copolymer-based dispersants were produced in situ by controlled heterophase polymerisation mediated by an amphiphilic macro-RAFT (reversible addition-fragmentation transfer agent. The stabilized CCNP aqueous dispersions were then applied on carbonate and silicate substrates; Scanning Electron Microscopy (SEManalysis of cross-sections allowed the evaluation of pore penetration, interfacial binding, and bridging (gap-filling properties of these novel consolidants.

  15. Mineralogical characteristics of Ettringites synthesized from solutions and suspensions

    International Nuclear Information System (INIS)

    Goetz-Neunhoeffer, F.; Neubauer, J.; Schwesig, P.

    2006-01-01

    Due to the wide technical importance of Ettringite (3CaO.Al 2 O 3 .3CaSO 4 .32H 2 O) in hydrated cement based systems, four different synthesis methods were applied to get a better overview on how and under what favoring conditions Ettringite can be formed. In the first step different precipitation methods resulting in Ettringite were established. For all methods Al 3+ was supplied by aqueous CO 2 -free solution of Al 2 (SO 4 ) 3 .18H 2 O. As a source of CaO-supply a clear solution and otherwise a Ca(OH) 2 -suspension was utilized. Four synthesis routes with and without sucrose were employed. Variation of reaction parameter like temperature, time of reaction, pH-value of synthesis solution and influence of additional Gypsum were investigated. The qualitative phase analysis was performed by X-ray diffraction method (XRD). Morphological aspects of some synthesis products were studied by scanning electron microscopy (SEM). Finally lattice and structural parameter of the Ettringites were determined by refinement of XRD-pattern using the Rietveld-Method

  16. Characteristics on electodynamic suspension simulator with HTS levitation magnet

    International Nuclear Information System (INIS)

    Lee, J.; Bae, D.K.; Sim, K.; Chung, Y.D.; Lee, Y.-S.

    2009-01-01

    High-T c superconducting (HTSC) electrodynamic suspension (EDS) system basically consists of the HTSC levitation magnet and the ground conductor. The levitation force of EDS system is forms by the interaction between the moving magnetic field produced by the onboard levitation magnet and the induced magnetic field produced by eddy current in the ground conductor. This paper deals with the characteristics of the EDS simulators with high-T c superconducting (HTS) levitation magnet. Two EDS simulator systems, rotating type EDS simulator and static type EDS simulator, were studied in this paper. The rotating type EDS simulator consists of a HTS levitation magnet and a 1.5 m diameter rotating ground conductor, a motor, the supporting structure and force measuring devices. In the static type EDS simulator, instead of moving magnetic field, AC current was applied to the fixed HTS levitation magnet to induce the eddy current. The static type EDS simulator consists of a HTS levitation magnet, a ground conductor, force measuring devices and supporting structure. The double-pancake type HTSC levitation magnet was designed, manufactured and tested in the EDS simulator.

  17. Characteristics on electodynamic suspension simulator with HTS levitation magnet

    Science.gov (United States)

    Lee, J.; Bae, D. K.; Sim, K.; Chung, Y. D.; Lee, Y.-S.

    2009-10-01

    High- Tc superconducting (HTSC) electrodynamic suspension (EDS) system basically consists of the HTSC levitation magnet and the ground conductor. The levitation force of EDS system is forms by the interaction between the moving magnetic field produced by the onboard levitation magnet and the induced magnetic field produced by eddy current in the ground conductor. This paper deals with the characteristics of the EDS simulators with high- Tc superconducting (HTS) levitation magnet. Two EDS simulator systems, rotating type EDS simulator and static type EDS simulator, were studied in this paper. The rotating type EDS simulator consists of a HTS levitation magnet and a 1.5 m diameter rotating ground conductor, a motor, the supporting structure and force measuring devices. In the static type EDS simulator, instead of moving magnetic field, AC current was applied to the fixed HTS levitation magnet to induce the eddy current. The static type EDS simulator consists of a HTS levitation magnet, a ground conductor, force measuring devices and supporting structure. The double-pancake type HTSC levitation magnet was designed, manufactured and tested in the EDS simulator.

  18. A novel magnetic lead screw active suspension system for vehicles

    DEFF Research Database (Denmark)

    Berg, Nick Ilsø; Holm, Rasmus Koldborg; Rasmussen, Peter Omand

    2014-01-01

    This paper encompasses a detailed study of the redesign of a novel Magnetic Lead Screw (MLS) active suspension system for possible regeneration of the energy dispatched in the suspension system and active control of vehicle body movement. The MLS converts a low speed high force linear motion...... of a translator into a high speed low torque rotational motion of a rotor through helically shaped magnets. The paper describes the drawback of the first MLS prototype v1.0 developed for active suspension system, which lead to a new design of the MLS prototype named v1.5. Furthermore the paper introduces detailed...

  19. Modelling nonlinear viscoelastic behaviours of loudspeaker suspensions-like structures

    Science.gov (United States)

    Maillou, Balbine; Lotton, Pierrick; Novak, Antonin; Simon, Laurent

    2018-03-01

    Mechanical properties of an electrodynamic loudspeaker are mainly determined by its suspensions (surround and spider) that behave nonlinearly and typically exhibit frequency dependent viscoelastic properties such as creep effect. The paper aims at characterizing the mechanical behaviour of electrodynamic loudspeaker suspensions at low frequencies using nonlinear identification techniques developed in recent years. A Generalized Hammerstein based model can take into account both frequency dependency and nonlinear properties. As shown in the paper, the model generalizes existing nonlinear or viscoelastic models commonly used for loudspeaker modelling. It is further experimentally shown that a possible input-dependent law may play a key role in suspension characterization.

  20. Correlated particle dynamics in concentrated quasi-two-dimensional suspensions

    International Nuclear Information System (INIS)

    Diamant, H; Cui, B; Lin, B; Rice, S A

    2005-01-01

    We investigate theoretically and experimentally how the hydrodynamically correlated lateral motion of particles in a suspension confined between two surfaces is affected by the suspension concentration. Despite the long range of the correlations (decaying as 1/r 2 with the inter-particle distance r), the concentration effect is present only at short inter-particle distances for which the static pair correlation is nonuniform. This is in sharp contrast with the effect of hydrodynamic screening in unconfined suspensions, where increasing the concentration changes the prefactor of the large-distance correlation

  1. A Kinematic, Kevlar(registered) Suspension System for an ADR

    Science.gov (United States)

    Voellmer, George M.; Jackson, Michael L.; Shirron, Peter J.; Tuttle, James G.

    2003-01-01

    The High Resolution Airborne Wideband Camera (HAWC) and the Submillimeter And Far Infrared Experiment (SAFIRE) will use identical Adiabatic Demagnetization Refrigerators (ADR) to cool their bolometer detectors to 200mK and 100mK, respectively. In order to minimize thermal loads on the salt pill, a Kevlar@ suspension system is used to hold it in place. An innovative, kinematic suspension system is presented. The suspension system is unique in that it consists or two parts that can be assembled and tensioned offline, and later bolted onto the salt pill. The resulting assembly constrains each degree of freedom only once, yielding a kinematic, tensile structure.

  2. On reactive suspension plasma spraying of calcium titanate

    OpenAIRE

    Kotlan, J. (Jiří); Pala, Z. (Zdeněk); Mušálek, R. (Radek); Ctibor, P. (Pavel)

    2016-01-01

    This study shows possibility of preparation of calcium titanate powder and coatings by reactive suspension plasma spraying. Suspension of mixture of calcium carbonate (CaCO3) and titanium dioxide (TiO2) powders in ethanol was fed into hybrid plasma torch with a DC-arc stabilized by a water–argon mixture (WSP-H 500). Various feeding distances and angles were used in order to optimize suspension feeding conditions. In the next step, the coatings were deposited on stainless steel substrates and ...

  3. A splitting integration scheme for the SPH simulation of concentrated particle suspensions

    Science.gov (United States)

    Bian, Xin; Ellero, Marco

    2014-01-01

    Simulating nearly contacting solid particles in suspension is a challenging task due to the diverging behavior of short-range lubrication forces, which pose a serious time-step limitation for explicit integration schemes. This general difficulty limits severely the total duration of simulations of concentrated suspensions. Inspired by the ideas developed in [S. Litvinov, M. Ellero, X.Y. Hu, N.A. Adams, J. Comput. Phys. 229 (2010) 5457-5464] for the simulation of highly dissipative fluids, we propose in this work a splitting integration scheme for the direct simulation of solid particles suspended in a Newtonian liquid. The scheme separates the contributions of different forces acting on the solid particles. In particular, intermediate- and long-range multi-body hydrodynamic forces, which are computed from the discretization of the Navier-Stokes equations using the smoothed particle hydrodynamics (SPH) method, are taken into account using an explicit integration; for short-range lubrication forces, velocities of pairwise interacting solid particles are updated implicitly by sweeping over all the neighboring pairs iteratively, until convergence in the solution is obtained. By using the splitting integration, simulations can be run stably and efficiently up to very large solid particle concentrations. Moreover, the proposed scheme is not limited to the SPH method presented here, but can be easily applied to other simulation techniques employed for particulate suspensions.

  4. Numerical Investigation of the Effect of Bottom Shape on the Flow Field and Particle Suspension in a DTB Crystallizer

    Directory of Open Access Journals (Sweden)

    Hao Pan

    2016-01-01

    Full Text Available The influence of the bottom shape on the flow field distribution and particle suspension in a DTB crystallizer was investigated by Computational Fluid Dynamics (CFD coupled with Two-Fluid Model (Eulerian model. Volume fractions of three sections were monitored on time, and effect on particle suspension could be obtained by analyzing the variation tendency of volume fraction. The results showed that the protruding part of a W type bottom could make the eddies smaller, leading to the increase of velocity in the vortex. Modulating the detailed structure of the W type bottom to make the bottom surface conform to the streamlines can reduce the loss of the kinetic energy of the flow fluid and obtain a larger flow velocity, which made it possible for the particles in the bottom to reach a better suspension state. Suitable shape parameters were also obtained; the concave and protruding surface diameter are 0.32 and 0.373 times of the cylindrical shell diameter, respectively. It is helpful to provide a theoretical guidance for optimization of DTB crystallizer.

  5. Effects of Atomization Injection on Nanoparticle Processing in Suspension Plasma Spray

    Directory of Open Access Journals (Sweden)

    Hong-bing Xiong

    2016-05-01

    Full Text Available Liquid atomization is applied in nanostructure dense coating technology to inject suspended nano-size powder materials into a suspension plasma spray (SPS torch. This paper presents the effects of the atomization parameters on the nanoparticle processing. A numerical model was developed to simulate the dynamic behaviors of the suspension droplets, the solid nanoparticles or agglomerates, as well as the interactions between them and the plasma gas. The plasma gas was calculated as compressible, multi-component, turbulent jet flow in Eulerian scheme. The droplets and the solid particles were calculated as discrete Lagrangian entities, being tracked through the spray process. The motion and thermal histories of the particles were given in this paper and their release and melting status were observed. The key parameters of atomization, including droplet size, injection angle and velocity were also analyzed. The study revealed that the nanoparticle processing in SPS preferred small droplets with better atomization and less aggregation from suspension preparation. The injection angle and velocity influenced the nanoparticle release percentage. Small angle and low initial velocity might have more nanoparticles released. Besides, the melting percentage of nanoparticles and agglomerates were studied, and the critical droplet diameter to ensure solid melting was drawn. Results showed that most released nanoparticles were well melted, but the agglomerates might be totally melted, partially melted, or even not melted at all, mainly depending on the agglomerate size. For better coating quality, the suspension droplet size should be limited to a critical droplet diameter, which was inversely proportional to the cubic root of weight content, for given critical agglomerate diameter of being totally melted.

  6. Gasification of peat and biomass in suspension. Turpeen ja biomassan suspensiokaasutus

    Energy Technology Data Exchange (ETDEWEB)

    Haukka, P.; Raiko, R.

    1993-01-01

    Gasification of peat and biomass in dilute particle-gas suspension has not been studied significantly in Finland, even though these fuels require drying, which often produces dry pulverized fuel. This report has concentrated on studying suitability of so-called two-stage entrained-bed gasification for peat and biomass. The gasification system consists of a pyrolysis reactor (entrained flow) and an adiabatic char combustor. Dry or almost dry fuel is fed into the hot flue gas stream coming from the char combustor. Gasification is based on flash pyrolysis in the dilute suspension flow. Residual char is separated from pyrolyzer gases in a gas cleaning device and fed back to the adiabatic combustor. In the combustor char is burned at high temperature to supply the heat required to support endothermic reactions occurring in the pyrolyzer. To study entrained-bed gasification two types of computer models were developed: steady state simulation model and kinetic pyrolyzer model. With the help of these computer models mass and energy balances of the gasifier can be solved and the main dimensions of the gasifier can be determined. Lack of proper kinetic parameters for fast pyrolysis of peat and biomass makes it more difficult to apply the kinetic model in practice. Quantitative data concerning fast pyrolysis in dilute gas-particle suspension are needed to be able to evaluate the performance of the suspension gasifier in more detail. Gasifier operation has been studied using three different levels for amounts of pyrolysis pro- ducts, nine pressure levels between 15-23 bars and five temperature levels between 800-1200 deg C. Furthermore, normal pressure performance was simulated. In addition to simulation studies product gas heating value was optimized

  7. Toward an Applied Administrative Science.

    Science.gov (United States)

    Dunbar, Roger L. M.

    1983-01-01

    A study of 65 articles from the 1981 volumes of "Administrative Science Quarterly" and "Harvard Business Review," using smallest space analysis, found that the few studies adopting subjective (instead of objective) approaches to analyzing organizational change were most likely to provide a basis for an applied administrative…

  8. Effect of body-weight suspension training versus treadmill training on gross motor abilities of children with spastic diplegic cerebral palsy.

    Science.gov (United States)

    Emara, Hatem A; El-Gohary, Tarek M; Al-Johany, Ahmed A

    2016-06-01

    Suspension training and treadmill training are commonly used for promoting functional gross motor skills in children with cerebral palsy. The aim of this study was to compare the effect of body-weight suspension training versus treadmill training on gross motor functional skills. Assessor-blinded, randomized, controlled intervention study. Outpatient rehabilitation facility. Twenty children with spastic diplegia (7 boys and 13 girls) in the age ranged from 6 to 8 years old were randomly allocated into two equal groups. All children were assessed at baseline, after 18-session and after 36-session. During the twelve-week outpatient rehabilitation program, both groups received traditional therapeutic exercises. Additionally, one group received locomotor training using the treadmill while the other group received locomotor training using body-weight suspension through the dynamic spider cage. Assessment included dimensions "D" standing and "E" walking of the gross motor function measure, in addition to the 10-m Walking Test and the five times sit to stand test. Training was applied three times per week for twelve consecutive weeks. No significant difference was found in standing or walking ability for measurements taken at baseline or after 18-session of therapy. Measurements taken at 36-session showed that suspension training achieved significantly (Ptraining for dimension D as well as for dimension E. No significant difference was found between suspension training and treadmill training regarding walking speed or sit to stand transitional skills. Body-weight suspension training is effective in improving walking and locomotor capabilities in children with spastic diplegia. After three month suspension training was superior to treadmill training. Body-weight suspension training promotes adequate postural stability, good balance control, and less exertion which facilitates efficient and safe gait.

  9. FORGING DEFECTS ANALYSIS IN SUSPENSION ARMAND FLASH CONTROL

    OpenAIRE

    Mr Jadhav Vijay B. , Prof. Mundhe V.L. , Dr. Narve N.G.

    2018-01-01

    The suspension arms in the process of fogging are made by different material and in that processes get various problems are found. In that paper list out that problem and solving flash wastage problem.

  10. Study of shear thickening behavior in colloidal suspensions

    Directory of Open Access Journals (Sweden)

    N Maleki Jirsaraee

    2015-01-01

    Full Text Available We studied the shear thickening behavior of the nano silica suspension (silica nanoparticles 12 nm in size suspended in ethylene glycol under steady shear. The critical shear rate for transition into shear thickening phase was determined at different concentrations and temperatures. The effect of temperature and concentration was studied on the shear thickening behavior. In silica suspension, it was observed that all the samples had a transition into shear thickening phase and also by increasing the temperature, critical shear rate increased and viscosity decreased. Our observations showed that movement in silica suspension was Brownian and temperature could cause a delay in transition into shear thickening phase. Yet, we observed that increasing the concentration would decrease critical shear rate and increase viscosity. Increasing temperature increased Brownian forces and increasing concentration increased hydrodynamic forces, confirming the contrast between these two forces for transition into shear thickening phase for the suspensions containing nano particles

  11. Degradability of aged aquatic suspensions of C60 nanoparticles

    DEFF Research Database (Denmark)

    Hartmann, B.; Buendia, Inmaculada M.; Baun, Anders

    2011-01-01

    While studies of the potential human and environmental effects of C60 and its derivatives are emerging in the scientific literature, the environmental fate of C60 is still largely unknown. In this study, aged aqueous suspensions of C60 (nC60) were investigated in the respirometric OECD test...... for ready biodegradability. Two suspensions of nC60 were prepared by stirring and aged under indirect exposure to sunlight for 36 months, which resulted in relatively stable suspensions with a dark-brown colour. The suspended nC60 could not be extracted into toluene and indicating that the particles were...... no longer present as underivatised nC60 but had undergone a transformation. TEM images and particle tracking analysis showed that the suspension consisted of particle aggregates with a size of 156 nm (SD=54nm) and 139nm (Sd=49), respectively, but also contained smaller aggregates. Samples of the nC60...

  12. Self-Suspended Suspensions of Covalently Grafted Hairy Nanoparticles

    KAUST Repository

    Choudhury, Snehashis; Agrawal, Akanksha; Kim, Sung A; Archer, Lynden A.

    2015-01-01

    length scales. On mesoscopic length scales, the suspensions display exceptional homogeneity and colloidal stability. We attribute this feature to steric repulsions between grafted chains and the space-filling constraint on the tethered chains

  13. Improved production of chlorogenic acid from cell suspension ...

    African Journals Online (AJOL)

    Chlorogenic acid is a free radical scavenger, antibacterial, anti- inflammatory, antiviral, hypoglycemic, and in addition to ... experiments, the effect of various strengths of B5 medium (1/4 .... Growth kinetics of L. macranthoides cell suspension ...

  14. Solution or suspension - Does it matter for lipid based systems?

    DEFF Research Database (Denmark)

    Larsen, A T; Holm, R; Müllertz, A

    2017-01-01

    In this study, the potential of co-administering an aqueous suspension with a placebo lipid vehicle, i.e. chase dosing, was investigated in rats relative to the aqueous suspension alone or a solution of the drug in the lipid vehicle. The lipid investigated in the present study was Labrafil M2125CS...... and three evaluated poorly soluble model compounds, danazol, cinnarizine and halofantrine. For cinnarizine and danazol the oral bioavailability in rats after chase dosing or dosing the compound dissolved in Labrafil M21515CS was similar and significantly higher than for the aqueous suspension....... For halofantrine the chase dosed group had a tendency towards a low bioavailability relative to the Labrafil M2125CS solution, but still a significant higher bioavailability relative to the aqueous suspension. This could be due to factors such as a slower dissolution rate in the intestinal phase of halofantrine...

  15. A simple route to prepare stable hydroxyapatite nanoparticles suspension

    International Nuclear Information System (INIS)

    Han Yingchao; Wang Xinyu; Li Shipu

    2009-01-01

    A simple ultrasound assisted precipitation method with addition of glycosaminoglycans (GAGs) is proposed to prepare stable hydroxyapatite (HAP) nanoparticles suspension from the mixture of Ca(H 2 PO 4 ) 2 solution and Ca(OH) 2 solution. The product was characterized by XRD, FT-IR, TEM, HRTEM and particle size, and zeta potential analyzer. TEM observation shows that the suspension is composed of 10-20 nm x 20-50 nm short rod-like and 10-30 nm similar spherical HAP nanoparticles. The number-averaged particle size of stable suspension is about 30 nm between 11.6 and 110.5 nm and the zeta potential is -60.9 mV. The increase of stability of HAP nanoparticles suspension mainly depends on the electrostatic effect and steric effect of GAGs. The HAP nanoparticles can be easily transported into the cancer cells and exhibit good potential as gene or drug carrier system.

  16. In vitro production of azadirachtin from cell suspension cultures of ...

    Indian Academy of Sciences (India)

    PRAKASH KUMAR G

    proven effective in the control of agricultural pests in an environmentally ..... Prakash G and Srivastava A K 2005 Statistical media optimization for cell growth and ... Juss. suspension cultures; Process Biochemistry 40 3795–3800. Prakash G ...

  17. Weakly sheared active suspensions: hydrodynamics, stability, and rheology.

    Science.gov (United States)

    Cui, Zhenlu

    2011-03-01

    We present a kinetic model for flowing active suspensions and analyze the behavior of a suspension subjected to a weak steady shear. Asymptotic solutions are sought in Deborah number expansions. At the leading order, we explore the steady states and perform their stability analysis. We predict the rheology of active systems including an activity thickening or thinning behavior of the apparent viscosity and a negative apparent viscosity depending on the particle type, flow alignment, and the anchoring conditions, which can be tested on bacterial suspensions. We find remarkable dualities that show that flow-aligning rodlike contractile (extensile) particles are dynamically and rheologically equivalent to flow-aligning discoid extensile (contractile) particles for both tangential and homeotropic anchoring conditions. Another key prediction of this work is the role of the concentration of active suspensions in controlling the rheological behavior: the apparent viscosity may decrease with the increase of the concentration.

  18. Optimal Vibration Control for Tracked Vehicle Suspension Systems

    Directory of Open Access Journals (Sweden)

    Yan-Jun Liang

    2013-01-01

    Full Text Available Technique of optimal vibration control with exponential decay rate and simulation for vehicle active suspension systems is developed. Mechanical model and dynamic system for a class of tracked vehicle suspension vibration control is established and the corresponding system of state space form is described. In order to prolong the working life of suspension system and improve ride comfort, based on the active suspension vibration control devices and using optimal control approach, an optimal vibration controller with exponential decay rate is designed. Numerical simulations are carried out, and the control effects of the ordinary optimal controller and the proposed controller are compared. Numerical simulation results illustrate the effectiveness of the proposed technique.

  19. Establishment of the callus and cell suspension culture of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2009-10-05

    Oct 5, 2009 ... Full Length Research Paper. Establishment of the callus ... study provided an efficient way for E. angustifolia cell suspension culture to produce secondary metabolite. .... was also observed that in these treatments the stem.

  20. Effective viscosity of 2D suspensions - Confinement effects

    Science.gov (United States)

    Peyla, Philippe; Priem, Stephane; Vincent, Doyeux; Farutin, Alexander; Ismail, Mourad

    2014-11-01

    We study the rheology of a sheared 2D suspension of non-Brownian disks in presence of walls. Although, it is of course possible today with modern computers and powerful algorithms to perform direct numerical simulations that fully account for multiparticle 3D interactions, the analysis of the simple case of a 2D suspension, provides valuable insights and helps to understand 3D results. For instance, we examine the role of particle-wall and particle-particle interactions in determining the rheology of confined sheared suspensions. In addition we evaluate the intrinsic viscosity as well as the contribution of hydrodynamic interactions to the dissipation as a function of a wide range of confinements. Thanks to the direct visualisation of the whole 2D Stokes flow, we are able to give a clear interpretation about the rheology of semi-dilute confined suspensions.

  1. Effect of the crone suspension control system on braking

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, X.; Oustaloup, A. [Bordeaux-1 Univ., Talence (France). Lab. d' Automatique et de Productique; Nouillant, C. [Bordeaux-1 Univ., Talence (France). Lab. d' Automatique et de Productique]|[DRIA-PSA Peugeot Citroen, Velizy - Villacoublay (France)

    2001-07-01

    Semi-active or active suspensions not only increase driving comfort, but also permit the control system to be switched over if required in order to improve the transmission of forces at the points of contact between tire and road surface by minimizing the dynamic wheel loads. It may also be possible to use these systems to control wheel load distribution and, thus, influence braking or steering performance by changing the distribution of normal forces between the front and rear axles. This article examines the effect of the CRONE suspension control system on braking. The central idea is to use continuously variable dampers and fast load levelling devices to distribute the normal forces of tire between the front and rear axles. The basis principle is explained using known dynamic properties of active suspension, vehicles and tires. The effect of active suspension on vehicle response during braking is then evaluated using computer simulations from a two-wheel vehicle model. (orig.)

  2. Establishment of sorghum cell suspension culture system for ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-03-18

    Mar 18, 2008 ... Additionally, sorghum cell suspension cultures have been initiated from the friable ... proteomics technologies. The field of proteomics is .... air dried at room temperature and resuspended in 2 ml of urea buffer [9 M urea, 2 M ...

  3. Structure and rheology of nanoparticle–polymer suspensions

    KAUST Repository

    Srivastava, Samanvaya; Shin, Jung Hwan; Archer, Lynden A.

    2012-01-01

    separation and aggregation than expected from theory for interacting brushes. SAXS and rheology measurements also reveal that at high particle loadings, the stabilizing oligomer brush is significantly compressed and produces jamming in the suspensions

  4. Rheological studies of aqueous stabilised nano-zirconia particle suspensions

    Directory of Open Access Journals (Sweden)

    Asad Ullah Khan

    2012-02-01

    Full Text Available In the present investigation aqueous suspensions of nano- and colloidal range particles are stabilised by changing the ambient pH. Rheology is used to establish the stability of the suspensions and it is found that the rheology of the suspensions is strongly dependent on the pH values. The viscosity is highest close to the iso-electric point of the powders. At the iso-electric point the net surface charge on the powder particles is zero and is the cause of the high viscosity. Away from the iso-electric point, the particles are charged, giving rise to a double layer phenomenon and causing the reduction in viscosity. It is also found that increasing the solid contents of the suspensions reduces the pH region of low viscosity.

  5. Well-dispersed gold nanowire suspension for assembly application

    International Nuclear Information System (INIS)

    Xu Cailing; Zhang Li; Zhang Haoli; Li Hulin

    2005-01-01

    A method for fabricating well-dispersed nanowire suspension has been demonstrated in the paper. Thin gold nanowires were prepared by template synthesis, and then functionalized with sulphonate group-terminated thiols before suspended in different solvents. The degree of aggregation of the obtained suspension was evaluated with transmission electron microscopy (TEM) and UV-vis spectroscopy. It was found that the degree of aggregation was predominated by the solvents, and the best degree of dispersion was obtained when isopropyl alcohol (IPA) was used as the solvent. The gold nanowires from the suspension can be selectively assembled onto chemically patterned substrates. This well-dispersed nanowire suspension is potentially useful for fabricating novel nanodevices

  6. Sugar transport by maize endosperm suspension cultures

    International Nuclear Information System (INIS)

    Felker, F.C.; Goodwin, J.C.

    1987-01-01

    To determine the mechanism of sugar uptake by suspension cultures derived from developing maize (Zea mays L.) endosperm, incorporation of radioactivity from 14 C-sugars by the tissue in the mid-log phase of growth was examined. Among the sugars tested was l'-deoxy-l'-fluorosucrose (FS), a derivative not hydrolyzed by invertase but recognized by sucrose carriers in other systems. At 40 mM, uptake of label from FS was 23% of that from sucrose, while uptake of label from L-glucose (used as a control for medium carry-over and adsorption) was 16% of that from sucrose. Uptake of label from sucrose did not increase at concentrations above 50 mM, possibly due to a rate-limiting requirement for extracellular hydrolysis. Kinetic analysis revealed both saturable and linear components of uptake for glucose and fructose. The rate of fructose uptake exceeded that of glucose at all concentrations. Fructose uptake at 20 mM was inhibited by NaN 3 , HgCl 2 , dinitrophenol, carbonyl cyanide m-chlorophenylhydrazone, and p-chloromercuribenzenesulfonic acid. Results suggest that sucrose is hydrolyzed prior to uptake, and that fructose is transported preferentially by a carrier sensitive to an external sulfhydryl group inhibitor. Metabolic activity is required for sugar uptake. The specificity of the hexose transporter is currently being investigated

  7. Acoustic manipulation of bacteria cells suspensions

    Science.gov (United States)

    GutiéRrez-Ramos, Salomé; Hoyos, Mauricio; Aider, Jean Luc; Ruiz, Carlos; Acoustofluidics Team Team; Soft; Bio Group Collaboration

    An acoustic contacless manipulation gives advantages in the exploration of the complex dynamics enviroment that active matter exhibits. Our works reports the control confinement and dispersion of Escherichia coliRP437-pZA3R-YFP suspensions (M9Glu-Ca) via acoustic levitation.The manipulation of the bacteria bath in a parallel plate resonator is achieved using the acoustic radiation force and the secondary radiation force. The primary radiation force generates levitation of the bacteria cells at the nodal plane of the ultrasonic standing wave generated inside the resonator. On the other side, secondary forces leads to the consolidation of stable aggregates. All the experiments were performed in the acoustic trap described, where we excite the emission plate with a continuous sinusoidal signal at a frequency in the order of MHz and a quartz slide as the reflector plate. In a typical experiment we observed that, before the input of the signal, the bacteria cells exhibit their typical run and tumble behavior and after the sound is turned on all of them displace towards the nodal plane, and instantaneously the aggregation begins in this region. CNRS French National Space Studies, CONACYT Mexico.

  8. Mirror suspension system for the TAMA SAS

    International Nuclear Information System (INIS)

    Takamori, Akiteru; Ando, Masaki; Bertolini, Alessandro; Cella, Giancarlo; DeSalvo, Riccardo; Fukushima, Mitsuhiro; Iida, Yukiyoshi; Jacquier, Florian; Kawamura, Seiji; Marka, Szabolcs; Nishi, Yuhiko; Numata, Kenji; Sannibale, Virginio; Somiya, Kentaro; Takahashi, Ryutaro; Tariq, Hareem; Tsubono, Kimio; Ugas, Jose; Viboud, Nicolas; Yamamoto, Hiroaki; Yoda, Tatsuo; Wang Chenyang

    2002-01-01

    Several R and D programmes are ongoing to develop the next generation of interferometric gravitational wave detectors providing the superior sensitivity desired for refined astronomical observations. In order to obtain a wide observation band at low frequencies, the optics need to be isolated from the seismic noise. The TAMA SAS (seismic attenuation system) has been developed within an international collaboration between TAMA, LIGO, and some European institutes, with the main objective of achieving sufficient low-frequency seismic attenuation (-180 dB at 10 HZ). The system suppresses seismic noise well below the other noise levels starting at very low frequencies above 10 Hz. It also includes an active inertial damping system to decrease the residual motion of the optics enough to allow a stable operation of the interferometer. The TAMA SAS also comprises a sophisticated mirror suspension subsystem (SUS). The SUS provides support for the optics and vibration isolation complementing the SAS performance. The SUS is equipped with a totally passive magnetic damper to suppress internal resonances without degrading the thermal noise performance. In this paper we discuss the SUS details and present prototype results

  9. Rheology of dense suspensions of non colloidal particles

    OpenAIRE

    Guazzelli , Elisabeth

    2017-01-01

    International audience; Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liq...

  10. Rheology of dense suspensions of non colloidal particles

    OpenAIRE

    Guazzelli Élisabeth

    2017-01-01

    Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical co...

  11. On reactive suspension plasma spraying of calcium titanate

    Czech Academy of Sciences Publication Activity Database

    Kotlan, Jiří; Pala, Zdeněk; Mušálek, Radek; Ctibor, Pavel

    2016-01-01

    Roč. 42, č. 3 (2016), s. 4607-4615 ISSN 0272-8842 R&D Projects: GA ČR GA15-12145S Institutional support: RVO:61389021 Keywords : Suspensions * X-raymethods * Perovskites * Substrates * Suspension plasma spraying Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 2.986, year: 2016 http://www.sciencedirect.com/science/article/pii/S0272884215022646

  12. Theory of superconducting magnet suspension: main results survey

    International Nuclear Information System (INIS)

    Voevodskii, K.E.; Kochetkov, V.M.

    1981-01-01

    A survey is given of theoretical achievements on electro-dynamic suspension of high speed ground vehicles with superconducting magnets. The problems discussed, are calculation of lift and drag forces acting on a superconducting magnet, the latter moving above a guideway structure which may be of two different types (either conducting sheet or a series of discrete loops); influence of irregularities of the guideway structure; vertical and longitudinal stability of suspension. (author)

  13. Viscosity, thermal diffusivity and Prandtl number of nanoparticle suspensions

    Institute of Scientific and Technical Information of China (English)

    WANG Buxuan; ZHOU Leping; PENG Xiaofeng

    2004-01-01

    Using our reported experimental data of effective thermal conductivity, specific heat capacity and viscosity for CuO nanoparticle suspensions, the corresponding thermal diffusivity and Prandtl number are calculated. With the hard sphere model and considering effects of particle clustering and surface adsorption, the increase of viscosity for nanoparticle suspension observed is explained. It is shown that the effective thermal conductivity will be strongly affected by the formation and correlated spatial distribution of nanoparticle clusters when compared to viscosity in hosting liquid.

  14. NMR water-proton spin-lattice relaxation time of human red blood cells and red blood cell suspensions

    International Nuclear Information System (INIS)

    Sullivan, S.G.; Rosenthal, J.S.; Winston, A.; Stern, A.

    1988-01-01

    NMR water-proton spin-lattice relaxation times were studied as probes of water structure in human red blood cells and red blood cell suspensions. Normal saline had a relaxation time of about 3000 ms while packed red blood cells had a relaxation time of about 500 ms. The relaxation time of a red blood cell suspension at 50% hematocrit was about 750 ms showing that surface charges and polar groups of the red cell membrane effectively structure extracellular water. Incubation of red cells in hypotonic saline increases relaxation time whereas hypertonic saline decreases relaxation time. Relaxation times varied independently of mean corpuscular volume and mean corpuscular hemoglobin concentration in a sample population. Studies with lysates and resealed membrane ghosts show that hemoglobin is very effective in lowering water-proton relaxation time whereas resealed membrane ghosts in the absence of hemoglobin are less effective than intact red cells. 9 refs.; 3 figs.; 1 table

  15. Complementary analysis techniques applied on optimizing suspensions of yttria stabilized zirconia

    DEFF Research Database (Denmark)

    Della Negra, Michela; Foghmoes, Søren Preben Vagn; Klemensø, Trine

    2016-01-01

    of dispersing agent and to optimize the dispersants concentration: Electrokinetic Sonic Amplitude was used to obtain zeta potential, Multiple Light Scattering for evaluating sedimentation rate, and multi-wavelength laser light scattering for measuring particle size distribution. All the results agree upon...

  16. A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Nazockdast, Ehssan, E-mail: ehssan@cims.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Center for Computational Biology, Simons Foundation, New York, NY 10010 (United States); Rahimian, Abtin, E-mail: arahimian@acm.org [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Zorin, Denis, E-mail: dzorin@cs.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Shelley, Michael, E-mail: shelley@cims.nyu.edu [Courant Institute of Mathematical Sciences, New York University, New York, NY 10012 (United States); Center for Computational Biology, Simons Foundation, New York, NY 10010 (United States)

    2017-01-15

    We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid–structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler–Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber–fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a cloud of semi-flexible fibers.

  17. A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

    International Nuclear Information System (INIS)

    Nazockdast, Ehssan; Rahimian, Abtin; Zorin, Denis; Shelley, Michael

    2017-01-01

    We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid–structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler–Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber–fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a cloud of semi-flexible fibers.

  18. A fast platform for simulating semi-flexible fiber suspensions applied to cell mechanics

    Science.gov (United States)

    Nazockdast, Ehssan; Rahimian, Abtin; Zorin, Denis; Shelley, Michael

    2017-01-01

    We present a novel platform for the large-scale simulation of three-dimensional fibrous structures immersed in a Stokesian fluid and evolving under confinement or in free-space in three dimensions. One of the main motivations for this work is to study the dynamics of fiber assemblies within biological cells. For this, we also incorporate the key biophysical elements that determine the dynamics of these assemblies, which include the polymerization and depolymerization kinetics of fibers, their interactions with molecular motors and other objects, their flexibility, and hydrodynamic coupling. This work, to our knowledge, is the first technique to include many-body hydrodynamic interactions (HIs), and the resulting fluid flows, in cellular assemblies of flexible fibers. We use non-local slender body theory to compute the fluid-structure interactions of the fibers and a second-kind boundary integral formulation for other rigid bodies and the confining boundary. A kernel-independent implementation of the fast multipole method is utilized for efficient evaluation of HIs. The deformation of the fibers is described by nonlinear Euler-Bernoulli beam theory and their polymerization is modeled by the reparametrization of the dynamic equations in the appropriate non-Lagrangian frame. We use a pseudo-spectral representation of fiber positions and implicit time-stepping to resolve large fiber deformations, and to allow time-steps not excessively constrained by temporal stiffness or fiber-fiber interactions. The entire computational scheme is parallelized, which enables simulating assemblies of thousands of fibers. We use our method to investigate two important questions in the mechanics of cell division: (i) the effect of confinement on the hydrodynamic mobility of microtubule asters; and (ii) the dynamics of the positioning of mitotic spindle in complex cell geometries. Finally to demonstrate the general applicability of the method, we simulate the sedimentation of a cloud of semi-flexible fibers.

  19. A magneto rheological hybrid damper for railway vehicles suspensions

    Directory of Open Access Journals (Sweden)

    Gheorghe GHITA

    2012-09-01

    Full Text Available High speed railway vehicles features a specific lateral oscillation resulting from the coupled lateral displacement and yaw of the wheelset which leads to a sinusoid movement of the wheelset along the track, transferred to the entire vehicle. The amplitude of this oscillation is strongly dependant on vehicle’s velocity. Over a certain value, namely the critical speed, the instability phenomenon so-called hunting occurs. To raise the vehicle’s critical speed different designs of the suspension all leading to a much stiffer vehicle can be envisaged. Different simulations prove that a stiffer central suspension will decrease the passenger’s comfort in terms of lateral accelerations of the carboy. The authors propose a semi-active magneto rheological suspension to improve the vehicle’s comfort at high speeds. The suspension has as executive elements hybrid magneto rheological dampers operating under sequential control strategy type balance logic. Using an original mathematical model for the lateral dynamics of the vehicle the responses of the system with passive and semi-active suspensions are simulated. It is shown that the semi-active suspension can improve the vehicle performances.

  20. Effect of suspension kinematic on 14 DOF vehicle model

    Science.gov (United States)

    Wongpattananukul, T.; Chantharasenawong, C.

    2017-12-01

    Computer simulations play a major role in shaping modern science and engineering. They reduce time and resource consumption in new studies and designs. Vehicle simulations have been studied extensively to achieve a vehicle model used in minimum lap time solution. Simulation result accuracy depends on the abilities of these models to represent real phenomenon. Vehicles models with 7 degrees of freedom (DOF), 10 DOF and 14 DOF are normally used in optimal control to solve for minimum lap time. However, suspension kinematics are always neglected on these models. Suspension kinematics are defined as wheel movements with respect to the vehicle body. Tire forces are expressed as a function of wheel slip and wheel position. Therefore, the suspension kinematic relation is appended to the 14 DOF vehicle model to investigate its effects on the accuracy of simulate trajectory. Classical 14 DOF vehicle model is chosen as baseline model. Experiment data is collected from formula student style car test runs as baseline data for simulation and comparison between baseline model and model with suspension kinematic. Results show that in a single long turn there is an accumulated trajectory error in baseline model compared to model with suspension kinematic. While in short alternate turns, the trajectory error is much smaller. These results show that suspension kinematic had an effect on the trajectory simulation of vehicle. Which optimal control that use baseline model will result in inaccuracy control scheme.

  1. Evaluating Suspension Formulations of Theophylline Cocrystals With Artificial Sweeteners.

    Science.gov (United States)

    Aitipamula, Srinivasulu; Wong, Annie B H; Kanaujia, Parijat

    2018-02-01

    Pharmaceutical cocrystals have garnered significant interest as potential solids to address issues associated with formulation development of drug substances. However, studies concerning the understanding of formulation behavior of cocrystals are still at the nascent stage. We present results of our attempts to evaluate suspension formulations of cocrystals of an antiasthmatic drug, theophylline, with 2 artificial sweeteners. Stability, solubility, drug release, and taste of the suspension formulations were evaluated. Suspension that contained cocrystal with acesulfame showed higher drug release rate, while a cocrystal with saccharin showed a significant reduction in drug release rate. The cocrystal with saccharin was found stable in suspension for over 9 weeks at accelerated test condition; in contrast, the cocrystal with acesulfame was found unstable. Taste analysis using an electronic taste-sensing system revealed improved sweetness of the suspension formulations with cocrystals. Theophylline has a narrow therapeutic index with a short half-life which necessitates frequent dosing. This adversely impacts patient compliance and enhances risk of gastrointestinal and cardiovascular adverse effects. The greater thermodynamic stability, sweetness, and sustained drug release of the suspension formulation of theophylline-saccharin could offer an alternative solution to the short half-life of theophylline and make it a promising formulation for treating asthmatic pediatric and geriatric patients. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

  2. Rheology of dense suspensions of non colloidal particles

    Science.gov (United States)

    Guazzelli, Élisabeth

    2017-06-01

    Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids that we will also address.

  3. Rheology of dense suspensions of non colloidal particles

    Directory of Open Access Journals (Sweden)

    Guazzelli Élisabeth

    2017-01-01

    Full Text Available Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing and in natural phenomena (e.g. flows of slurries, debris, and lava. Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers or non-Newtonian fluids that we will also address.

  4. Robustness analysis of bogie suspension components Pareto optimised values

    Science.gov (United States)

    Mousavi Bideleh, Seyed Milad

    2017-08-01

    Bogie suspension system of high speed trains can significantly affect vehicle performance. Multiobjective optimisation problems are often formulated and solved to find the Pareto optimised values of the suspension components and improve cost efficiency in railway operations from different perspectives. Uncertainties in the design parameters of suspension system can negatively influence the dynamics behaviour of railway vehicles. In this regard, robustness analysis of a bogie dynamics response with respect to uncertainties in the suspension design parameters is considered. A one-car railway vehicle model with 50 degrees of freedom and wear/comfort Pareto optimised values of bogie suspension components is chosen for the analysis. Longitudinal and lateral primary stiffnesses, longitudinal and vertical secondary stiffnesses, as well as yaw damping are considered as five design parameters. The effects of parameter uncertainties on wear, ride comfort, track shift force, stability, and risk of derailment are studied by varying the design parameters around their respective Pareto optimised values according to a lognormal distribution with different coefficient of variations (COVs). The robustness analysis is carried out based on the maximum entropy concept. The multiplicative dimensional reduction method is utilised to simplify the calculation of fractional moments and improve the computational efficiency. The results showed that the dynamics response of the vehicle with wear/comfort Pareto optimised values of bogie suspension is robust against uncertainties in the design parameters and the probability of failure is small for parameter uncertainties with COV up to 0.1.

  5. Development of A New Automotive Active Suspension System

    Science.gov (United States)

    Yousef Abdulhammed, Eng.; Eng. Hisham Elsherif, Dr, Prof.

    2017-12-01

    The main objective was to develop a smart new vehicle suspension system that minimizes the road irregularities impact on the driver, also to increase performance and stability of the vehicle at high speeds. The central idea is based on modifying the normal passive suspension system into a computer controller hydraulic actuated active suspension system simply by adding a new component such as a hydraulic cylinder on a normal passive system. The new suspension system is economical to be wildly used in consumer’s cars with low prices. The new added components was analytically tested and modeled according to different parameters. A new test rig was implemented to simulate a real quarter suspension system. The new suspension model was controlled by feedback controller according to the road conditions; the controller output controls the cylinder actuator to compensate the road oscillations and increases the vehicle stability for the passenger. Finally, to maximize the aerodynamics coefficients of the vehicle during high speeds by controlling the vehicle clearance level from the ground to achieve full stability, steering and fuel economy.

  6. Analysis of Train Suspension System Using MR dampers

    Science.gov (United States)

    RamaSastry, DVA; Ramana, K. V.; Mohan Rao, N.; Siva Kumar, SVR; Priyanka, T. G. L.

    2016-09-01

    This paper deals with introducing MR dampers to the Train Suspension System for improving the ride comfort of the passengers. This type of suspension system comes under Semi-active suspension system which utilizes the properties of MR fluid to damp the vibrations. In case of high speed trains, the coach body is subjected to vibrations due to vertical displacement, yaw and pitch movements. When the body receives these disturbances from the ground,the transmission of vibrations to the passenger increases which affect the ride comfort. In this work, the equations of motion of suspension system are developed for both conventional passive system and semi-active system and are modelled in Matlab/Simulink and analysis has been carried out. The passive suspension system analysis shows that it is taking more time to damp the vibrations and at the same time the transmissibility of vibrations is more.Introducing MR dampers,vertical and angular displacements of the body are computed and compared. The results show that the introduction of MR dampers into the train suspension system improves ride comfort.

  7. Clay-cement suspensions - rheological and functional properties

    Science.gov (United States)

    Wojcik, L.; Izak, P.; Mastalska-Poplawska, J.; Gajek, M.

    2017-01-01

    The piping erosion in soil is highly unexpected in civil engineering. Elimination of such damages is difficult, expensive and time-consuming. One of the possibility is the grouting method. This method is still developed into direction of process automation as well as other useful properties of suspensions. Main way of modernization of the grouting method is connected it with rheology of injection and eventuality of fitting them to specific problems conditions. Very popular and useful became binders based on modified clays (clay-cement suspensions). Important principle of efficiency of the grouting method is using of time-dependent pseudothixotropic properties of the clay-cement suspensions. The pseudo-rheounstability aspect of the suspensions properties should be dedicated and fitted to dynamic changes of soil conditions destructions. Whole process of the modification of the suspension rheology is stimulated by the specific agents. This article contains a description of practical aspects of the rheological parameters managing of the clay-cement suspensions, dedicated to the building damages, hydrotechnic constructions etc.

  8. Estudo de suspensões de bentonitas sob diferentes condições térmicas Study of bentonit suspensions under different thermal conditions

    Directory of Open Access Journals (Sweden)

    C. A. Leal

    2013-03-01

    envelhecimento tem influência direta no comportamento reológico das dispersões avaliadas.Clay suspensions are used as drilling fluids for the initial rock layers, usually constituted of unconsolidated sediments. For deeper layers oil based fluids are more commonly used due to their thermal resistance. Therefore, because of the environmental laws, these fluids are being replaced and the clay suspensions arise as an alternative, as they are environmentally correct and have lower cost. So, it becomes of great importance to study the properties of clay suspensions at moderate and high temperatures. This work has the aim to evaluate the properties of bentonit clay suspensions under different thermal conditions. For so, a type 2² factorial plan with three experiments in the centre + star configuration, was applied, totalizing 11 experimental runs to evaluate the influence of temperature and clay content (entrance variables over the rheological and filtration properties of the clay suspensions. The clay suspensions were prepared with bentonit concentrations between 8.75 g/350 mL and 22.4 g/350 mL and were submitted to temperatures between 38 ºC and 176 ºC during 16 h. Two types of thermal aging were studied, dynamic and static, in a Fann Roller Oven equipment. The rheological properties (apparent viscosity - AV and plastic viscosity - PV were determined in a Fann 35A viscometer and the filtered volume (FV in a API filter-press. Could be concluded that the entrance variables did influence statistically, at a 95% confidence level, on the dispersion properties, being observed that the combination of elevated temperatures and high clay concentrations leads to higher values of VA and VP, as for the higher values of VF were obtained from the suspensions prepared with lower clay concentrations and submitted to higher temperature. It became evident that the type of aging does have direct influence in the rheological behaviors of the evaluated dispersions.

  9. 3D modeling design and engineering analysis of automotive suspension beam

    Directory of Open Access Journals (Sweden)

    Ju Zhi Lan

    2016-01-01

    Full Text Available Automotive suspension is an important device for transmission and torque. The main parameters and dimensions of 40 tons of heavy duty truck spring suspension system are designed in the paper. According to the data, the 3D modeling and virtual assembly of the leaf spring suspension are carried out by using parametric design. Structural stress of spring suspension is analyzed which can provide a guide and basis for the design of the leaf spring suspension.

  10. Proceedings of the Joint Magnetism and Magnetic Materials-Intermag Conference (6th) Held in Albuquerque, New Mexico on 20-23 June 1994. Journal of Applied Physics. Volume 76. Number 10. Part 2

    Science.gov (United States)

    1994-06-23

    frequency but also on the transverse permeability a. If A is a Fe4,3Co68.2Si12.. sBl 5 . In a low frequency range of 1-10 kHz, sensitive function of an...effective field at the nucleus, Bpp is the ’)Permanent address: Dept. of Electronics, Fukuoka Institute of Technology, applied field, Bani is the

  11. Model predictive control of an air suspension system with damping multi-mode switching damper based on hybrid model

    Science.gov (United States)

    Sun, Xiaoqiang; Yuan, Chaochun; Cai, Yingfeng; Wang, Shaohua; Chen, Long

    2017-09-01

    This paper presents the hybrid modeling and the model predictive control of an air suspension system with damping multi-mode switching damper. Unlike traditional damper with continuously adjustable damping, in this study, a new damper with four discrete damping modes is applied to vehicle semi-active air suspension. The new damper can achieve different damping modes by just controlling the on-off statuses of two solenoid valves, which makes its damping adjustment more efficient and more reliable. However, since the damping mode switching induces different modes of operation, the air suspension system with the new damper poses challenging hybrid control problem. To model both the continuous/discrete dynamics and the switching between different damping modes, the framework of mixed logical dynamical (MLD) systems is used to establish the system hybrid model. Based on the resulting hybrid dynamical model, the system control problem is recast as a model predictive control (MPC) problem, which allows us to optimize the switching sequences of the damping modes by taking into account the suspension performance requirements. Numerical simulations results demonstrate the efficacy of the proposed control method finally.

  12. Effect of particle size on laser-induced breakdown spectroscopy analysis of alumina suspension in liquids

    Energy Technology Data Exchange (ETDEWEB)

    Diaz Rosado, Jose Carlos [CEA, DEN, SEARS, LANIE, 91191 Gif-sur-Yvette (France); Univ. Paris Sud, Faculty of Pharmaceutical Sciences, Public Health and Environment UMR 8079, 5 rue J.B. Clement, 92296 Chatenay-Malabry (France); National University of Engineering, Faculty of Science, P.O. Box 31-139, Av. Tupac Amaru 210, Lima (Peru); L' hermite, Daniel, E-mail: daniel.lhermite@cea.fr [CEA, DEN, SEARS, LANIE, 91191 Gif-sur-Yvette (France); Levi, Yves [Univ. Paris Sud, Faculty of Pharmaceutical Sciences, Public Health and Environment UMR 8079, 5 rue J.B. Clement, 92296 Chatenay-Malabry (France)

    2012-08-15

    The analysis by Laser Induced Breakdown Spectroscopy (LIBS) was proposed for the detection and the quantification of different elements in water even when the analyte is composed of particles in suspension. We have studied the effect of particle size on the LIBS signal during liquid analysis. In our study we used different particle sizes (from 2 {mu}m to 90 {mu}m) of Al{sub 2}O{sub 3} in suspension in water. The results were compared to the signal obtained in the case of dissolved aluminum. In the case of particles, a linear correlation between the LIBS signal versus concentration was found but a significant decrease in the slope of the calibration curve was found when the particle size increased. Several hypotheses have been tested and only a partial ablation of the particles might explain this decrease in signal intensity. This effect probably does not occur at smaller particle size. We estimated 860 nm/pulse as ablated thickness from the top of the particle. A statistical analysis over all data obtained allowed us to calculate 100 {mu}m as ablated water column depth. - Highlights: Black-Right-Pointing-Pointer We have identified a decrease of calibration curve when particle size increases. Black-Right-Pointing-Pointer Partial particle ablation has been identified as the origin of this effect. Black-Right-Pointing-Pointer The ablation rate on Al{sub 2}O{sub 3} particles in suspension in water has been estimated. Black-Right-Pointing-Pointer We can determine the deepness of the interaction volume into the liquid.

  13. Preparing hydroxyapatite-silicon composite suspensions with homogeneous distribution of multi-walled carbon nano-tubes for electrophoretic coating of NiTi bone implant and their effect on the surface morphology

    International Nuclear Information System (INIS)

    Khalili, Vida; Khalil-Allafi, Jafar; Xia, Wei; Parsa, Alireza B.; Frenzel, Jan; Somsen, Christoph; Eggeler, Gunther

    2016-01-01

    Graphical abstract: - Highlights: • The stable composite suspensions of hydroxyapatite, silicon and multi-walled carbon nano-tubes was prepared using functionalization of and multi-walled carbon nano-tubes in HNO_3 vapor and triethanolamine as dispersing agent. • The zeta potential of composite suspensions is less than that of hydroxyapatite suspension. • The silicon particles presence in suspension causes to decrease the charge carrier in suspension and current density during electrophoretic deposition. • The orientation of multi-walled carbon nano-tubes to parallel direction of the applied electric field during electrophoretic deposition can facilitate their moving towards the cathode and increase current density. • The more zeta potential of suspension, the lower roughness of coatings during electrophoretic deposition. - Abstract: Preparing a stable suspension is a main step towards the electrophoretically depositing of homogeneous and dense composite coatings on NiTi for its biomedical application. In the present study, different composite suspensions of hydroxyapatite, silicon and multi-walled carbon nano-tubes were prepared using n-butanol and triethanolamine as media and dispersing agent, respectively. Multi-walled carbon nanotubes were first functionalized in the nitric acid vapor for 15 h at 175 °C, and then mixed into suspensions. Thermal desorption spectroscopy profiles indicate the formation of functional groups on multi-walled carbon nano-tubes. An excellent suspension stability can be achieved for different amounts of triethanolamine. The amount of triethanolamine can be increased by adding a second component to a stable hydroxyapatite suspension due to an electrostatic interaction between components in suspension. The stability of composite suspension is less than that of the hydroxyapatite suspension, due to density differences, which under the gravitational force promote the demixing. The scanning electron microscopy images of the

  14. H∞ control of railway vehicle suspension with MR damper using scaled roller rig

    International Nuclear Information System (INIS)

    Shin, Yu-Jeong; You, Won-Hee; Hur, Hyun-Moo; Park, Joon-Hyuk

    2014-01-01

    In this paper, a magneto-rheological (MR) damper was applied to the secondary suspension to reduce the vibration of a car body. The control performance of the MR damper was verified by numerical analysis with a 1/5 scale railway vehicle model in accordance with the similarity law. The analysis results were then validated in tests. In particular, the objective of the study was to understand how the control performance affected the dynamic characteristics of a railway vehicle and to systematically analyze the relationship between control performance and dynamic characteristics depending on various running speeds. To achieve this, experimental results for the dynamic characteristics of the scaled MR damper designed for the 1/5 scale railway vehicle model were applied to the railway vehicle model. The H ∞ control method was applied to the controller. The means of designing the railway vehicle body vibration controller and the effectiveness of its results were studied. (paper)

  15. Contribution to the study of the physical stability of the suspensions of zinc oxide, titanium dioxide and precipitated sulphur employing emulsified solid greases like vehicle

    International Nuclear Information System (INIS)

    Porras Navarro, Martha

    2001-01-01

    This research evaluated the physical stability of the suspensions of zinc oxide, precipitated sulphur and titanium dioxide. By using emulsified vehicles of three solid greases: stearilic alcohol, stearic acid and beeswax. That varies the concentration of solid grease (2%, 4%, 6 %) and the velocity of agitation for the emulsified vehicle's preparation (250, 500, 750 revolutions by minutes). That got 81 suspensions, 27 for every grease employed. The following effects there were evaluated like indicators of the physical stability of the suspensions: volume of sediment, apparent viscosity, facility of resuspension. There was effected an analysis of the varying of two controlled factors to establish the importance since the statistical viewpoint of the variants of the process over the volume of the sediment. This study indicates that the selection of solid grease is an parameter which influence is significant, what supports the got data through the research. By giving as a result that the stearilic alcohol is the most competent vehicle for the preparation of these suspensions. (Author) [es

  16. Applied probability and stochastic processes

    CERN Document Server

    Sumita, Ushio

    1999-01-01

    Applied Probability and Stochastic Processes is an edited work written in honor of Julien Keilson. This volume has attracted a host of scholars in applied probability, who have made major contributions to the field, and have written survey and state-of-the-art papers on a variety of applied probability topics, including, but not limited to: perturbation method, time reversible Markov chains, Poisson processes, Brownian techniques, Bayesian probability, optimal quality control, Markov decision processes, random matrices, queueing theory and a variety of applications of stochastic processes. The book has a mixture of theoretical, algorithmic, and application chapters providing examples of the cutting-edge work that Professor Keilson has done or influenced over the course of his highly-productive and energetic career in applied probability and stochastic processes. The book will be of interest to academic researchers, students, and industrial practitioners who seek to use the mathematics of applied probability i...

  17. Effects of Hydrostatic Loading on a Self-Aggregating, Suspension Culture–Derived Cartilage Tissue Analog

    Science.gov (United States)

    Kraft, Jeffrey J.; Jeong, Changhoon; Novotny, John E.; Seacrist, Thomas; Chan, Gilbert; Domzalski, Marcin; Turka, Christina M.; Richardson, Dean W.; Dodge, George R.

    2011-01-01

    Objective: Many approaches are being taken to generate cartilage replacement materials. The goal of this study was to use a self-aggregating suspension culture model of chondrocytes with mechanical preconditioning. Design: Our model differs from others in that it is based on a scaffold-less, self-aggregating culture model that produces a cartilage tissue analog that has been shown to share many similarities with the natural cartilage phenotype. Owing to the known loaded environment under which chondrocytes function in vivo, we hypothesized that applying force to the suspension culture–derived chondrocyte biomass would improve its cartilage-like characteristics and provide a new model for engineering cartilage tissue analogs. Results: In this study, we used a specialized hydrostatic pressure bioreactor system to apply mechanical forces during the growth phase to improve biochemical and biophysical properties of the biomaterial formed. We demonstrated that using this high-density suspension culture, a biomaterial more consistent with the hyaline cartilage phenotype was produced without any foreign material added. Unpassaged chondrocytes responded to a physiologically relevant hydrostatic load by significantly increasing gene expression of critical cartilage molecule collagen and aggrecan along with other cartilage relevant genes, CD44, perlecan, decorin, COMP, and iNOS. Conclusions: This study describes a self-aggregating bioreactor model without foreign material or scaffold in which chondrocytes form a cartilage tissue analog with many features similar to native cartilage. This study represents a promising scaffold-less, methodological advancement in cartilage tissue engineering with potential translational applications to cartilage repair. PMID:26069584

  18. Rotational magnetic pulses enhance the magnetofection efficiency in vitro in adherent and suspension cells

    International Nuclear Information System (INIS)

    Dahmani, Ch.; Mykhaylyk, O.; Helling, Fl.; Götz, St.; Weyh, Th.; Herzog, H.-G.; Plank, Ch.

    2013-01-01

    The association of magnetic nanoparticles with gene delivery vectors in combination with the use of gradient magnetic fields (magnetofection) enables improved and synchronised gene delivery to cells. In this paper, we report a system comprising rotating permanent magnets to generate defined magnetic field pulses with frequencies from 2.66 to 133 Hz and a field amplitude of 190 or 310 mT at the location of the cells. Low-frequency pulses of 2.66–10 Hz with a magnetic flux density of 190 mT were applied to the examined cells for 30–120 s after magnetofection. These pulses resulted in a 1.5–1.9-fold enhancement in the transfection efficiency compared with magnetofection with only a static magnetic field in both adherent and suspension cells. The magnetic field amplitudes of 190 and 310 mT had similar effects on the transfection efficacy. No increase in the percentage of transgene-expressing suspension cells and no cytotoxic effects (based on the results of the MTT assay) were observed after applying alternating magnetic fields. - Highlights: ► We developed a magnetic system capable of generating defined magnetic pulses based on permanent magnets. ► The main advantage of the system is the lack of heat-induced fluctuations in the working parameters. ► Our system succeeded in enhancing the transfection of adherent human lung epithelial cells and human suspension cells. ► The enhancement in the transfection efficiency compared with static magnetic field is due to the magnetic field pulses. ► The approach could be used as a complementary method for drug targeting

  19. Trends in hydraulic fracturing distributions and treatment fluids, additives, proppants, and water volumes applied to wells drilled in the United States from 1947 through 2010: data analysis and comparison to the literature

    Science.gov (United States)

    Gallegos, Tanya J.; Varela, Brian A.

    2015-01-01

    Hydraulic fracturing is presently the primary stimulation technique for oil and gas production in low-permeability, unconventional reservoirs. Comprehensive, published, and publicly available information regarding the extent, location, and character of hydraulic fracturing in the United States is scarce. This national spatial and temporal analysis of data on nearly 1 million hydraulically fractured wells and 1.8 million fracturing treatment records from 1947 through 2010 (aggregated in Data Series 868) is used to identify hydraulic fracturing trends in drilling methods and use of proppants, treatment fluids, additives, and water in the United States. These trends are compared to the literature in an effort to establish a common understanding of the differences in drilling methods, treatment fluids, and chemical additives and of how the newer technology has affected the water use volumes and areal distribution of hydraulic fracturing. Historically, Texas has had the highest number of records of hydraulic fracturing treatments and associated wells in the United States documented in the datasets described herein. Water-intensive horizontal/directional drilling has also increased from 6 percent of new hydraulically fractured wells drilled in the United States in 2000 to 42 percent of new wells drilled in 2010. Increases in horizontal drilling also coincided with the emergence of water-based “slick water” fracturing fluids. As such, the most current hydraulic fracturing materials and methods are notably different from those used in previous decades and have contributed to the development of previously inaccessible unconventional oil and gas production target areas, namely in shale and tight-sand reservoirs. Publicly available derivative datasets and locations developed from these analyses are described.

  20. Analytical scale purification of zirconia colloidal suspension using field programmed sedimentation field flow fractionation.

    Science.gov (United States)

    Van-Quynh, Alexandra; Blanchart, Philippe; Battu, Serge; Clédat, Dominique; Cardot, Philippe

    2006-03-03

    Sedimentation field flow fractionation was used to obtain purified fractions from a polydispersed zirconia colloidal suspension in the potential purpose of optical material hybrid coating. The zirconia particle size ranged from 50/70 nm to 1000 nm. It exhibited a log-Gaussian particle size distribution (in mass or volume) and a 115% polydispersity index (P.I.). Time dependent eluted fractions of the original zirconia colloidal suspension were collected. The particle size distribution of each fraction was determined with scanning electron microscopy and Coulter sub-micron particle sizer (CSPS). These orthogonal techniques generated similar data. From fraction average elution times and granulometry measurements, it was shown that zirconia colloids are eluted according to the Brownian elution mode. The four collected fractions have a Gaussian like distribution and respective average size and polydispersity index of 153 nm (P.I. = 34.7%); 188 nm (P.I. = 27.9%); 228 nm (P.I. = 22.6%), and 276 nm (P.I. = 22.3%). These data demonstrate the strong size selectivity of SdFFF operated with programmed field of exponential profile for sorting particles in the sub-micron range. Using this technique, the analytical production of zirconia of given average size and reduced polydispersity is possible.